Salmonella typhimurium infection occurred in a children's zoo where 11 fowl and 85 mammals were kept. Initially, the guinea pigs were infected and transmitted the infection to the fowl and rabbits. These mammals responded to medication and cleared of the infection; however, the birds were judged to contain excreters despite four regimens of treatment with antibiotics. Cloacal swabs were taken from all the birds. One turkey was positive for Salmonella and was destroyed. Pooled fecal samples from the birds were again positive. All the birds were tested serologically, and two birds, a goose and a turkey, were positive with Salmonella pullorum-gallinarum antigen, which was assumed to be a cross reaction with S. typhimurium antigen. The two birds were destroyed and the goose yielded Salmonella. The infection was finally eradicated, and the serologic examination was considered to be the most useful procedure for detection of the excreters.