A gourmet caterer who had nine stores in the northern Virginia-DC-Baltimore, Maryland metropolitan area was associated with outbreaks of Cyclospora. Groups of persons developed cyclosporiasis after group luncheons. Eating dishes that contained fresh basil increased the risk of illness. A produce supplier for company A provided most of the supply of basil for the time frame of exposure. However, this produce supplier also supplied produce for other outlets, and the other outlets did not appear to be associated with the outbreak.