Clostridium botulinum was inoculated into hamburger, sausage and turkey sandwiches, which were subsequently placed in a nitrogen atmosphere. Growth of the bacterium was studied to assess the botulism hazard. Hamburgers inoculated with C. botulinum types A and B and incubated at room temperature became toxic on day 4 while remaining fully acceptable organoleptically. Sausages became toxic on day 7 while appearing marginally acceptable. In air at room temperature, all sandwiches were obviously decomposed before toxin was produced. Refrigeration under nitrogen prevented toxin production by types A and B; however, hamburgers inoculated with type E were toxic at 12 C in 30 days while appearing fully acceptable. All refrigerated sandwiches were either fully or marginally acceptable organoleptically throughout the 60-day observation period; none were obviously decomposed. Turkey sandwiches did not become toxic at any temperature or incubation time studied.