BACKGROUND: Declines due to Papaya ringspot virus (PRSV) are the primary constraint limiting production of papaya (Carica papaya L.) in tropical and subtropical regions. Given the lack of suitable sources of resistance in the genus, transgenic papayas carrying the coat protein gene of a local strain of PRSV were recently developed to manage the disease in Jamaica. For assurance of food safety, a 90 day subchronic whole-food feeding study in rats was conducted with transgenic and non-transgenic papayas. RESULTS: Male and female Wistar rats (N = 56) received diets containing transgenic or non-transgenic papayas at twice the equivalent of the average daily human consumption of fresh papayas. No adverse effects on animal behaviour or differences in body weight and organ weight between the animal groups (P &lt; 0.05) were observed during the study. Necropsy at the end of the study indicated that neither pathological nor histopathological abnormalities were present in the liver and kidneys of rats in the control and treated groups. In addition, the levels of activity of plasma, liver and kidney acid and alkaline phosphatases and alanine and aspartate transaminases were comparable (P &lt; 0.05). Although significant differences (P &lt; 0.05) were found in the cholesterol and triglyceride levels in the plasma and liver among animals of the treated groups, overall the values were comparable to those of the control. CONCLUSION: The results suggest that consumption of transgenic papayas may not have adverse effects in rats as regards the parameters considered in this study.