Epidemiologic studies of possible effects of agricultural environments upon human health suffer from lack of reliable pesticides usage data. The Arkansas Reproductive Health Monitoring System has developed a method for estimating specific pesticides usage annually for sub-county regions, including amounts, application method, and months. This method is applied to 39 regions of 8 central Arkansas counties for 1980-82. The hugh variability of pesticides usage on individual crops demonstrates the inaccuracy likely if general survey estimates are employed. Annual usage of pesticides in a single sub-county region of 53,000 hectares (130,880 land acres) was greater than 1/2 million pounds (248,670 kg) of 60 pesticides, 40 of which were applied during a four month period. The multiplicity and variability of pesticides usage indicate the need for locally developed pesticides data for epidemiologic studies and for combined studies across regions with widely differing agricultural practices.