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I'm currently trying out the new MemoryCache in .Net 4 to cache a few bits of data in one of our apps. The trouble I have is the objects are updated and the cache appears to be persisting the changes e.g. public IEnumerable<SomeObject> GetFromDatabase(){ const string _cacheKeyGetDisplayTree = "SomeKey"; ObjectCache _cache = MemoryCache.Default; var objectInCache = _cache.Get(_cacheKeyGetDisplayTree) as IEnumerable<SomeObject>; if (objectInCache != null) return objectInCache.ToList(); // Do something to get the items _cache.Add(_cacheKeyGetDisplayTree, categories, new DateTimeOffset(DateTime.UtcNow.AddHours(1))); return categories.ToList(); } public IEnumerable<SomeObject> GetWithIndentation(){ var categories = GetFromDatabase(); foreach (var c in categories) { c.Name = "-" + c.Name; } return categories; } If I were calling GetWithIndentation() first and then later calling GetFromDatabase() I would expect it to return the original list of SomeObject but instead it returns the modified items (with "-" prefixed on the name). I thought ToList() destroyed the reference but it still seems to persist the changes. I'm sure it's obvious but can anyone spot where I'm going wrong?

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