The majority of cases of aplastic anemia, a rare previously lethal disease, are of unknown etiology. Nevertheless, for the past 3 decades, case reports and case series of aplastic anemia have suggested an etiologic association between aplastic anemia and pesticide exposure. A review of the medical literature, including basic science literature, confirms a possible etiologic association between pesticide exposure and aplastic anemia. Two hundred and eighty cases of aplastic anemia associated with pesticide exposure were reported in the literature. The majority of these cases were young (mean age, 34 years; median, 28), with a short latency (mean, 5 months) and with a history of occupational exposure to pesticides. The pesticide exposures reported were the organochlorines and organophosphates, both commonly used pesticides throughout the world. Therapeutic and methodologic issues as well as future directions for research into this etiologic association are discussed.