A total of 41 persons with the same strains of Salmonella Typhimurium were reported from several states between November 1, 2013 and May 3, 2014. Epidemiologic and laboratory findings linked these Salmonella Typhimurium infections to exposure to various clinical and college and university teaching microbiology laboratories. Among 28 ill persons with available information, 10 (36%) were hospitalized. No deaths were reported. Eighteen (86%) of 21 ill persons interviewed reported being enrolled in either a human biology course or microbiology course. Fifteen (83%) of these 18 ill persons were students, and three (22%) were employees. Many ill persons reported several behaviors while they were working in the laboratory that would increase the risk of acquiring a Salmonella infection, including not wearing gloves or lab coats, lack of handwashing, and using the same writing utensils and notebooks outside of the laboratory. Additionally, many ill persons did not recall receiving laboratory safety training.