Alfalfa sprouts were first linked to Salmonella Muenchen illnesses in Wisconsin in September. Eventually six other states detected Salmonella Muenchen illnesses related to alfalfa sprout consumption. The food histories of the first 16 case patients were traced back to Wisconsin sprout distributors A, B, and C and to Wisconsin sprouters A and B. The Wisconsin sprouters routinely disinfected sprouts according to a then recommended procedure. Environmental samples from Wisconsin sprouters A and B yielded no bacterial isolates. Sprout samples yielded S. Arizona and S. Muenchen. A FDA researcher had unexpectedly found S. Muenchen in alfalfa seed from seed lot COA98. This seed had been distributed to 33 sprouters in 10 states. The distribution of the seed corresponded with where illness had occurred.