An empirically fitted Rydberg-like formula for two-electron systems is described. The resultant revised Rydberg formula (RRF) contains two parameters: the screening constant sigma and the correction to the effective quantum number mu . They can concisely correlate a large number of (core)n/sub /il² binding energies. Both are simple functions of the core charge Z, the core configuration and l. The accuracy of the RRF in calculating the two-electron binding energies of over 50 (core)n/sub /is² species is demonstrated and the physical interpretations of sigma _s and mu _s are discussed.