An outbreak of cyclosporiasis occurred among attendees of two events held on 24 July in different counties in Missouri. Restrospective cohort studies of the 2 clusters of cases, which comprised 62 case patients, strongly associated the chicken pasta salad, served at one event, and the tomato basil salad, served at the other event, with illness. The most likely vehicle of infection was fresh basil, which was included in both salads. The basil had been obtained from the same distributor and was either grown in Mexico or the United States. Laboratory analysis of the leftover chicken pasta salad yielded Cyclospora DNA and 1 sporulated Cyclospora oocyst.