For geneticists and other researchers alike it is often useful to know how many related proteins might perform similar functions. With this in mind, a survey was performed to determine what proportion of human and Drosophila genes code for Ras superfamily members and their positive or negative regulators. Results indicate that just < 2% of genes in both genomes predict such proteins. A database was compiled to provide easy access to this information. This database also includes information on approximately 360 putative Ras superfamily effector proteins and may be a useful tool for those interested in GTPase biology.