A multi-serotype outbreak of Salmonella was linked to alfalfa sprouts grown by a southern California sprout grower and to alfalfa seeds grown in southern California. Salmonella Havana (18 cases) and Salmonella Cubana (22 cases) were the Salmonella strains associated with this outbreak. The outbreak strains of both S. Havana and S. Cubana were isolated from the same lot of alfalfa seeds used by the California sprout grower. In addition, they were identified in a sample of alfalfa seeds used by a Maryland sprout grower. The California sprout grower disinfected the seed with a chlorine bleach solution. This sprout grower showed no evidence of factors that could contribute to contamination or cross-contamination of seeds. The implicated seeds were supplied by a seed mill from southern California and had been grown in southern California. The mixing of seed lots at the mill precluded identification of a single seed grower.