The Salmonella/microsome assay and the micronucleus test were employed to evaluate the chronic toxicity potential of environmental degradative products of alachlor. Degradative products include 2-hydroxy-2',6'-diethyl-N-(methoxymethyl)acetanilide ; 2-chloro-2',6'-diethylacetanilide ; 2,6-diethylacetanilide; 2,6-diethylaniline ; 2,6-diethyl-N-(methoxymethyl)aniline ; 2-hydroxy-2',6'-diethylacetanilide; and 2,6-diethyl-N-(methoxymethyl)acetanilide. 2-Hydroxy-2',6'-diethylacetanilide and 2-chloro-2',6'-diethylacetanilide were weakly mutagenic to Salmonella strain TA100, with reversion rates of 54.6 and 58.4 His + revertants/μmol, respectively. Reversion was dependent on bioactivation with phenobarbitol-induced microsomes. Addition of the reduced form of glutathione to the assay system resulted in decreased mutagenicity of 2-hydroxy-2',6'-diethylacetanilide, suggesting that these products may act as toxic electrophiles that bind directly to DNA/RNA. None of the environmental degradative products tested acted as clastogens in the micronucleus test, even at near-lethal doses (ca. 500 μg/g). Only 2-hydroxy-2',6'-diethyl-N-(methoxymethyl)acetanilide cross-reacts (ca. 40%) with commercially available alachlor immunoassay test kits. The two mutagenic compounds did not cross-react.