In the present work, a direct count procedure designed for the assessment of the decay rates of nonradiative processes in polyatomic molecules has been introduced. Using the described approach the internal conversion (IC) decay rates of a considerable number of single vibronic levels (SVL) in S-1 benzene have been estimated. The decay rates of "bright" SVLs were found to increase only slowly, while those of "dark," out-of-plane modes containing states grew far more rapidly with the excess vibrational energy E(v) in S-1. The observed behavior with E(v) as well as the absolute magnitude of the calculated IC decay rates were in general conformity with the existing experimental evidence.