After the Puerto Rico Department of Health received a report of salmonellosis in an infant who had contact with a pet turtle, we conducted a case-control study in two urban areas in Puerto Rico to measure the extent of pet turtle-associated salmonellosis there. Ten (17%) of 60 infants with salmonellosis but none of their matched controls had a history of exposure to a pet turtle in the two weeks before onset of illness. Two other case patients were also exposed to a pet turtle--an 8-year-old child and an adult with acquired immunodeficiency syndrome and Salmonella bacteremia. A variety of Salmonella serogroups were represented in the turtle-associated cases. All turtle lots collected from pet shops in Puerto Rico were culture-positive for Salmonella; 89% yielded Salmonella pomona. Contamination of the turtles probably occurred at the farm before distribution, since S pomona was also isolated from turtles exported from the same farm to Guam and to Yugoslavia. The estimated 3 to 4 million turtles exported annually from the United States are an important potential route for global dissemination of human salmonellosis.