[en] Both the post-replication and the excision repair mechanism participate in the induction of Trp+ revertants in Escherichia coli B/r Hcr+ thy trp after a UV-irradiation. At low radiation doses (surviving cell fraction > 10-1) most Trp+ reversions are du to the post-replication repair mechanism while at high doses (surviving cell fraction < 10-1) the Trp+ reversions arise probably as the result of inaccurate excision repair. The absolute accuracy of repair processes decreases with increasing radiation doses. (author)