The California Department of Health Services identified a cluster of infections caused by Salmonella Kottbus. Using a standard food history questionnaire, alfalfa sprouts were determined to be the only probable cause of the infections. More cases were identified, and a traceback was initiated. This investigation led to the identification of a single sprout producer of all the contaminated sprouts, Fuji Natural Foods of Ontario. A single seed lot was used during the period associated with the growth of the contaminated sprouts, and these had been imported from Australia. Although all the seeds from that lot were past there sell-by date, the producer issued a voluntary recall. A culture of a sample of this seed lot yielded Salmonella Kottbus. Cultures from the floor drains in the production facility also yielded Salmonella Kottbus. Patient, seed, and environmental isolates were genetic matches to one another.