Thirty-one persons who ate from a Stanford University fraternity kitchen became infected with Salmonella typhosa in May 1967. The source of the outbreak remains undetermined. The chief manifestations of the disease were fever and headache. No patient was severely ill. Diagnostic clues were a high percentage of nonsegmented neutrophils on blood smears and an increased Widal's reaction in previously unimmunized patients ill more than six days. Positive stool and blood cultures were readily found. Seventeen patients were treated with 3 gm daily of chloramphenicol for two weeks and all recovered with no sequelae. One individual, never ill, remains a carrier. Prior immunization probably lengthens the incubation period and may be associated with amelioration of the disease.