A questionnaire, medical records, and blood and urine samples were used to survey instances of occupationally related hospitalization among 102 workers at a pesticide facility in rural Arkansas that manufactured 1-lambda-methylthioethylideneamino methyl carbamate (16752775) (methomyl) and 3,4-dichloropropionanilide (709988) (propanil), a herbicide made from 3,4-dichloraniline (95761). Packaging workers had the highest rate of illness and hospitalization, and experienced blurred vision or pupillary constriction. Production workers exposed to dichloroaniline and propanil had the highest incidence of chloracne. Rabbit ear tests verified the chloracnegenic potential of propanil and 3,4- dichloroaniline. The authors conclude that a hazard exists in the manufacture and formulation of pesticides and herbicides, and report that industrial hygiene improvements in the packaging area have decreased the illness rate at the pesticide facility surveyed.