In the period April 1–15, 1977, nine residents of one Nebraska town experienced violent illnesses with short duration following ingestion of locally grown hydroponic cucumbers. Despite a thorough Investigation, the etiologic agent of illness was not determined. From July 16–25, 1978, a second similar outbreak occurred in an adjacent city. Five individuals experienced illness similar to that which occurred in 1977, also following ingestion of hydroponic cucumbers grown at the same greenhouse Involved in the 1977 outbreak. The carbamate insecticide, aidicarb, was detected in some cucumbers grown at the hydroponic greenhouse. The source of this chemical in the greenhouse could not be determined.