Between May and October 2000, the Regional Health Office of Kolda Region in the south of Senegal, West Africa, reported an epidemic of an unknown illness characterized by thoracic pain, dyspnea and edemas of limb and face. The epidemic covered a radius of approximately 40 km (24 miles) between the districts of Kolda and Sedhiou in Kolda Region. Cases were mostly men whose age ranged between 12 and 60 years old. Investigation revealed that they had been exposed to pesticides distributed by the government to groundnut farmers. The signs and symptoms suggested intoxication with carbamates, carbofurans, and possibly thiram, contained in the pesticides distributed with the groundnut seeds. Government distribution created an excessive use of pesticides in the farms, and consequently an overexposure of the subjects who handled the seeders, especially young males but also a small proportion of women who worked in the groundnut fields. Many of these subjects, not accustomed to handle pesticides, came to overestimate the quantity of product to fill the seeder. It should be noted that the policy of distribution of pesticides in Senegal, which presents risk of poisoning, was not systematically accompanied by sufficient information on the danger of the products and of certain precautions that should be taken during their use.