Background: The aim of this study was to compare the health status data of 4449 adults with intellectual disabilities (ID) aged 40 years and older, from three international sites and identify cross-cultural trends in the prevalence of age-associated organ system morbidities. Study group: Data from samples of older adults with ID in Taiwan, Israel and New York State, United States, collected in three previous studies, were combined for analysis using multivariate logistic regression analyses. Methods: All data were collected using the Rochester Health Status Survey (RHSS), a survey instrument designed to collect data on demographics, morbidity, and health services usage of adults with ID through chart-review by a medical professional. Results: Irrespective of site, the likelihood of the presence of auditory problems, gastrointestinal, cardiovascular, infectious disease, eye, musculoskeletal, and respiratory conditions in people with ID increased with age and the likelihood of the presence of dermatological, endocrine, and psychiatric conditions did not increase with age. Conclusions: Prevalence of organ system diseases with increasing age in people with ID seems to be similar to expected patterns in reference population data for people without ID. The data suggest that it could be useful to increase vigilance, preventive measures, and appropriate screenings for people with ID, similar to efforts that have been incorporated in general practice guidelines. Such efforts may be useful in the delay of onset and/or reduction of the prevalence of some morbidities and secondary disability-related conditions in people with ID. Further studies are needed in these areas.