Yes indeed. This cannot change. And is guaranteed by the nature of the how keys() and values() are implemented in native hashes (non-magical). Basically they are both achieved by walking the bucket array from left to right and within a bucket from top to bottom. Since they both do the same data structure walk they both return the same results. However note this is true only of a /given/ hash. You can't assume that one hashes keys() will match another's values() even if they contain the same list of keys().