Epidemic cholera struck Peru in January 1991 and spread within a month to the Amazon headwaters. A case-control study was done in the Amazonian city of Iquitos, Peru. Cholera-like illness was associated with eating unwashed fruits and vegetables (odds ratio [OR] = 8.0; 95% confidence limits [CL] = 2.2, 28.9) and drinking untreated water (OR = 2.9; 95% CL = 1.3, 6.4). Consumption of a drink made from toronja, a citrus fruit, was protective against illness (OR = 0.4; 95% CL = 0.2, 0.7). Illness was inversely associated with the quantity of toronja drink consumed (P < .01). Produce has not previously been convincingly documented as a risk factor for cholera; this study underscores the importance of washing produce before eating it. Acidic juices, such as toronja drink (pH 4.1), inhibit vibrio growth and may make contaminated water safer. Wild citrus fruits such as toronja are abundant, cheap, and popular in the Amazon region. Promoting the consumption of toronja drink may be a useful cholera prevention strategy in this region.