42 compounds identified in pulp mill effluent were screened for genetic activity in growing yeast cells using strains D7 and XV185-14C without S9. In addition to 3 of these compounds that had been shown previously to be mutagenic in Salmonella. 5 more were mutagenic in strain XV185-14C. All 8 induced 2-5-fold increases in reversion frequencies over background at the trp5 locus--5 of these induced 1.5-3-fold increases at the hom3 locus and 1 induced a doubling at his1. None of the compounds induced absolute increases of gene convertants per plate in strain D7, although 3 showed increased convertant frequencies as survival decreased.