In September 1988 we investigated reports of seizures in persons who had eaten taquitos, a commercially prepared snack food. We identified and interviewed 5 persons with new-onset seizures within 12 hours of eating taquitos, all purchased during a 1-week period from a single store. Leftover taquitos were found to contain endrin, a highly toxic chlorinated hydrocarbon pesticide. Although tissue confirmation of exposure to endrin was not possible and the level of contamination in the tested taquitos was below that previously thought to be capable of inducing seizures, the pattern of symptoms and the common time and place of purchase strongly suggested that the seizures were due to endrin-contaminated taquitos. The source of endrin contamination could not be determined. This episode is the first report of illness associated with endrin-contaminated food products in the United States.