Abstract
This paper discusses an application of the stochastic model of carcinogenesis proposed by Yakovlev and Polig to the analysis of experimental data on multiple pulmonary tumors induced by urethane. The results of this analysis suggest that the rate of administration of urethane has no effect on the mean number of initiated cells per unit dose. Likewise, the formation of lesions responsible for cell death appears to be unaffected by the dose rate.