Growth of Salmonella typhimurium LT-2 (Loeffler) Cast. and Chalm. was inhibited by 3-amino-l,2,4-triazole (amitrole), and 3-hydroxy-1,2,4-triazole, 3-chloro-l,2,4-triazole, and 5-amino-1,2,3,4-tetrazole (hereinafter referred to respectively as hydroxytriazole, chlorotriazole, and aminotetrazole). Toxicity of 2 × 10−2 M amitrole was partially overcome by 2 × 10−4 M histidine, and more effectively circumvented by combinations of histidine with 2 × 10−4 M adenine, 2 × 10−4 M riboflavin, or 2 × 10−4 M methionine. Serine reduced toxicity of 10−1 M amitrole when combined with both histidine and adenine but was less effective than methionine. Hydroxytriazole inhibition was partially overcome by adenine or less effectively by histidine but not by riboflavin, methionine, or serine. Chlorotriazole and aminotetrazole inhibitions were circumvented by 2 × 10−4 M methionine, 10−3 M serine, and 10−4 M cysteine but not by histidine, adenine, or riboflavin. The toxicity of high concentrations (10−3 M) of cysteine was reduced by chlorotriazole and aminotetrazole.