Streptomycessp. PS1/5 was able to degrade atrazine in soil while growing on a mixture of chitin and ground cornstalks as carbon and nitrogen source. The addition of triple superphosphate greatly stimulated the degradation of atrazine byStreptomycessp. PS1/5, while the addition of lime stimulated the degradation to a lesser degree. Ferrous sulfate had a small positive effect on atrazine degradation. Atrazine in soil was reduced from 20 g g‘1dry soil (20 ppm) to 6 ppm within 30 days in soil amended with 8% chitin, 2% cornstalks and 0.1% triple superphosphate and incubated at 25°C. The results indicate that it may be possible to use bacteria of the genusStreptomycesto degrade pesticide residues in contaminated soils.