Men who have moderate occupational exposure to pesticides were selected as subjects for these long-term studies. The results of a series of clinical and biochemical tests are compared with those of a closely matched control group. No effects of clinical significance were observed in the occupationally exposed men despite increased storage of pesticides in their bodies. A number of seasonal, occupational, clinical, and biochemical variations between the two groups are reported. The differences are slight and of questionable significance to health, whether associated with pesticides or not. Abnormalities may be discovered as research is continued, testing procedures refined, and additional parameters investigated.