The emergence of new network interface technology is enabling new approaches to the development of communications software. This paper evaluates the SHRIMP virtual memory mapped network interface by using it to build two fast implementations of remote procedure call (RPC). Our first implementations, called vRPC, is fully compatible with the SunRPC standard. We change the RPC runtime library, the operating system kernel is unchanged, and only a minimal change was needed in the stub generator to create a new protocol identifier. Despite these restrictions, our vRPC implementation is several times faster than existing SunRPC implementations. A round-trip null RPC with no arguments and results under vRPC takes about 33 μs. Our second implementation, called ShrimpRPC, is not compatible with SunRPC but offers much better performance. ShrimpRPC specializes the stub generator and runtime library to take full advantage of SHRIMP's features. The result is a round-trip null RPC latency of 9.5 μs, which is about 1 μs above the hardware minimum.