The effect of two pesticides, oxamyl and chlordane, on nontarget soil biota were examined in microcosms. Neither oxamyl nor chlordane had an effect on rates of litter decomposition or soil and litter respiration. There were differences in numbers of nematodes and protozoans and in biomass of bacteria and fungi in microcosms with and without chlordane on some sampling dates. One of the nematodes, Pelodera sp., died out in all of the microcosms within 30 days. Although the pesticide chlordane had no measurable effect on the activities of the soil biota as measured by respiration and mass loss, it did affect the population sizes and biomass of some grazers of soil biota.