Remote computing resource service providers allow customers to execute one or more applications in a virtual environment on computer systems provided by the computing resource service provider. The virtual machines may be managed by a hypervisor executing on computer systems operated by the service provider. The virtual machines' memory may be protected by a memory obfuscation service and the hypervisor. The memory obfuscation service may enable the virtual machines to maintain at least a portion of sensitive information in an obfuscated format. The virtual machines may request access to the virtual machines' memory, the memory obfuscation service may obtain the requested memory in an obfuscated format and un-obfuscate the memory such that it may be used by the virtual machines.