In this paper we present formulas to compute the busy cycle renewal function for the M|G|00 queue. It's value in t gives the mean number of busy periods that begin in [0, t].
We consider service time distributions for wich the renewal function is given for a simple expression and others for wich it is more complicated, namely: exponential, NBUE (New Better Than Used in Expectation), NWUE (New Worse Than Used in Expectation), DFR (Decreasing Failure Rate), IMRL (Increasing Mean Residual Life) and power function.

keywords: M|G|00, busy cycle, renewal function.