From the comparison of the results of model and experimental kinetics of thrombocytopoiesis the following parameters have been quantitatively estimated: (1) the percentage of cells killed during the interphase (interphase death) and (2) the duration of the mitosis delay and the abortive rise. There was a 1.3-1.5-fold and 2-3-fold nonspecific and postirradiation, respectively, decrease in the megacaryocyte maturation time. The transit time of the committed megacaryocyte precursors was reduced due to death of premature precursors and survival of mature forms.