diff --git a/src/libextra/serialize.rs b/src/libextra/serialize.rs
index 6b298d877da..e7ccb91fb75 100644
--- a/src/libextra/serialize.rs
+++ b/src/libextra/serialize.rs
@@ -426,18 +426,6 @@ impl<D:Decoder,T:Decodable<D> + 'static> Decodable<D> for @T {
     }
 }
 
-impl<S:Encoder,T:Encodable<S>> Encodable<S> for @mut T {
-    fn encode(&self, s: &mut S) {
-        (**self).encode(s)
-    }
-}
-
-impl<D:Decoder,T:Decodable<D> + 'static> Decodable<D> for @mut T {
-    fn decode(d: &mut D) -> @mut T {
-        @mut Decodable::decode(d)
-    }
-}
-
 impl<'a, S:Encoder,T:Encodable<S>> Encodable<S> for &'a [T] {
     fn encode(&self, s: &mut S) {
         s.emit_seq(self.len(), |s| {
diff --git a/src/libstd/clone.rs b/src/libstd/clone.rs
index b383c9edf36..b26ceb799a7 100644
--- a/src/libstd/clone.rs
+++ b/src/libstd/clone.rs
@@ -58,12 +58,6 @@ impl<T> Clone for @T {
     fn clone(&self) -> @T { *self }
 }
 
-impl<T> Clone for @mut T {
-    /// Return a shallow copy of the managed box.
-    #[inline]
-    fn clone(&self) -> @mut T { *self }
-}
-
 impl<'a, T> Clone for &'a T {
     /// Return a shallow copy of the borrowed pointer.
     #[inline]
@@ -168,14 +162,6 @@ impl<T: Freeze + DeepClone + 'static> DeepClone for @T {
     fn deep_clone(&self) -> @T { @(**self).deep_clone() }
 }
 
-// FIXME: #6525: should also be implemented for `T: Send + DeepClone`
-impl<T: Freeze + DeepClone + 'static> DeepClone for @mut T {
-    /// Return a deep copy of the managed box. The `Freeze` trait is required to prevent performing
-    /// a deep clone of a potentially cyclical type.
-    #[inline]
-    fn deep_clone(&self) -> @mut T { @mut (**self).deep_clone() }
-}
-
 macro_rules! deep_clone_impl(
     ($t:ty) => {
         impl DeepClone for $t {
@@ -239,23 +225,6 @@ fn test_managed_clone() {
     assert_eq!(a, b);
 }
 
-#[test]
-fn test_managed_mut_deep_clone() {
-    let x = @mut 5i;
-    let y: @mut int = x.deep_clone();
-    *x = 20;
-    assert_eq!(*y, 5);
-}
-
-#[test]
-fn test_managed_mut_clone() {
-    let a = @mut 5i;
-    let b: @mut int = a.clone();
-    assert_eq!(a, b);
-    *b = 10;
-    assert_eq!(a, b);
-}
-
 #[test]
 fn test_borrowed_clone() {
     let x = 5i;
diff --git a/src/libstd/default.rs b/src/libstd/default.rs
index aaba23c683b..60f38e3b3de 100644
--- a/src/libstd/default.rs
+++ b/src/libstd/default.rs
@@ -16,10 +16,6 @@ pub trait Default {
     fn default() -> Self;
 }
 
-impl<T: Default + 'static> Default for @mut T {
-    fn default() -> @mut T { @mut Default::default() }
-}
-
 impl<T: Default + 'static> Default for @T {
     fn default() -> @T { @Default::default() }
 }
diff --git a/src/libstd/managed.rs b/src/libstd/managed.rs
index 7322f0b0647..c5705665896 100644
--- a/src/libstd/managed.rs
+++ b/src/libstd/managed.rs
@@ -31,13 +31,6 @@ pub fn ptr_eq<T>(a: @T, b: @T) -> bool {
     a_ptr == b_ptr
 }
 
-/// Determine if two mutable shared boxes point to the same object
-#[inline]
-pub fn mut_ptr_eq<T>(a: @mut T, b: @mut T) -> bool {
-    let (a_ptr, b_ptr): (*T, *T) = (to_unsafe_ptr(&*a), to_unsafe_ptr(&*b));
-    a_ptr == b_ptr
-}
-
 #[cfg(not(test))]
 impl<T:Eq> Eq for @T {
     #[inline]
@@ -46,14 +39,6 @@ impl<T:Eq> Eq for @T {
     fn ne(&self, other: &@T) -> bool { *(*self) != *(*other) }
 }
 
-#[cfg(not(test))]
-impl<T:Eq> Eq for @mut T {
-    #[inline]
-    fn eq(&self, other: &@mut T) -> bool { *(*self) == *(*other) }
-    #[inline]
-    fn ne(&self, other: &@mut T) -> bool { *(*self) != *(*other) }
-}
-
 #[cfg(not(test))]
 impl<T:Ord> Ord for @T {
     #[inline]
@@ -66,41 +51,18 @@ impl<T:Ord> Ord for @T {
     fn gt(&self, other: &@T) -> bool { *(*self) > *(*other) }
 }
 
-#[cfg(not(test))]
-impl<T:Ord> Ord for @mut T {
-    #[inline]
-    fn lt(&self, other: &@mut T) -> bool { *(*self) < *(*other) }
-    #[inline]
-    fn le(&self, other: &@mut T) -> bool { *(*self) <= *(*other) }
-    #[inline]
-    fn ge(&self, other: &@mut T) -> bool { *(*self) >= *(*other) }
-    #[inline]
-    fn gt(&self, other: &@mut T) -> bool { *(*self) > *(*other) }
-}
-
 #[cfg(not(test))]
 impl<T: TotalOrd> TotalOrd for @T {
     #[inline]
     fn cmp(&self, other: &@T) -> Ordering { (**self).cmp(*other) }
 }
 
-#[cfg(not(test))]
-impl<T: TotalOrd> TotalOrd for @mut T {
-    #[inline]
-    fn cmp(&self, other: &@mut T) -> Ordering { (**self).cmp(*other) }
-}
-
 #[cfg(not(test))]
 impl<T: TotalEq> TotalEq for @T {
     #[inline]
     fn equals(&self, other: &@T) -> bool { (**self).equals(*other) }
 }
 
-#[cfg(not(test))]
-impl<T: TotalEq> TotalEq for @mut T {
-    #[inline]
-    fn equals(&self, other: &@mut T) -> bool { (**self).equals(*other) }
-}
 #[test]
 fn test() {
     let x = @3;
diff --git a/src/libstd/num/mod.rs b/src/libstd/num/mod.rs
index 8dbec0f63c6..d66d13657fc 100644
--- a/src/libstd/num/mod.rs
+++ b/src/libstd/num/mod.rs
@@ -1079,11 +1079,6 @@ pub fn pow_with_uint<T:NumCast+One+Zero+Div<T,T>+Mul<T,T>>(radix: uint, pow: uin
     total
 }
 
-impl<T: Zero + 'static> Zero for @mut T {
-    fn zero() -> @mut T { @mut Zero::zero() }
-    fn is_zero(&self) -> bool { (**self).is_zero() }
-}
-
 impl<T: Zero + 'static> Zero for @T {
     fn zero() -> @T { @Zero::zero() }
     fn is_zero(&self) -> bool { (**self).is_zero() }
diff --git a/src/libstd/repr.rs b/src/libstd/repr.rs
index 2f9478716a3..e60abed42f2 100644
--- a/src/libstd/repr.rs
+++ b/src/libstd/repr.rs
@@ -655,13 +655,10 @@ fn test_repr() {
     exact_test(&(~"he\u10f3llo"), "~\"he\\u10f3llo\"");
 
     exact_test(&(@10), "@10");
-    exact_test(&(@mut 10), "@mut 10");
-    exact_test(&((@mut 10, 2)), "(@mut 10, 2)");
     exact_test(&(~10), "~10");
     exact_test(&(&10), "&10");
     let mut x = 10;
     exact_test(&(&mut x), "&mut 10");
-    exact_test(&(@mut [1, 2]), "@mut [1, 2]");
 
     exact_test(&(0 as *()), "(0x0 as *())");
     exact_test(&(0 as *mut ()), "(0x0 as *mut ())");
diff --git a/src/libstd/to_bytes.rs b/src/libstd/to_bytes.rs
index 9de812ed385..bd1c49c6c24 100644
--- a/src/libstd/to_bytes.rs
+++ b/src/libstd/to_bytes.rs
@@ -319,13 +319,6 @@ impl<A:IterBytes> IterBytes for @A {
     }
 }
 
-impl<A:IterBytes> IterBytes for @mut A {
-    #[inline]
-    fn iter_bytes(&self, lsb0: bool, f: Cb) -> bool {
-        (**self).iter_bytes(lsb0, f)
-    }
-}
-
 impl<A:IterBytes> IterBytes for Rc<A> {
     #[inline]
     fn iter_bytes(&self, lsb0: bool, f: Cb) -> bool {