A descriptive epidemiologic study, conducted in Costa Rica, investigated the incidence of pesticide poisonings with special attention to agricultural workers and occupational exposure. Information from three national registers (occupational accident and disease reports, hospitalizations, and deaths) were used. During 1986, 1800 occupational accidents caused by pesticides were reported; between 1980 and 1986 altogether 3330 persons were hospitalized and 429 died. Cholinesterase inhibitors caused 71% of the reported occupational accidents, 63% of the hospitalizations, and 36% of the deaths. Paraquat caused 21% of the occupational accidents, 24% of the hospitalizations, and 60% of the deaths. Hospitalizations and deaths were 13 and 11 times, respectively, more frequent among agricultural workers than among the rest of the population. High-risk groups for occupational poisonings included agricultural workers aged 15-29 years, female workers, and banana plantation workers. The yearly incidence of symptomatic occupational pesticide poisonings among agricultural workers was estimated at 4.5%.