[en] Data on 946 skin cancers treated by radiation were used to estimate the importance of repopulation. Six different treatment regimes were used, from a single dose to 74 Gy given in 47 fractions. High local control of the small skin cancers (L 1 cm) was independent of dose fractionation. For large tumors, only 74 Gy in 47 fractions was the optimal treatment. Time factor analysis showed a steep increase in the NTD50 values between day 28 and 65 of treatment. This implies that tumor clonogen repopulation starts around 4 weeks of treatment. The present results show a three-component dose-response curve instead of the two-component curves which were found for head and neck and bladder cancer. (author) 1 tab., 2 figs., 15 refs