This paper discusses preliminary work on standardizing and implementing a remote procedure call (RPC) mechanism for grid computing. The GridRPC API is designed to address one of the factors that has hindered widespread acceptance of grid computing -- the lack of a standardized, portable, and simple programming interface. In this paper, we examine two concrete implementations of the GridRPC API based on two different grid computing systems: NetSolve and Ninf. Our initial work on GridRPC shows that client access to existing grid computing systems such as NetSolve and Ninf can be unified via a common API, a task that has proven to be problematic in the past. In addition to these existing grid computing systems, the minimal API defined in this paper provides a basic mechanism for implementing a wide variety of other grid-aware applications and services.