In February 1990 a World Health Organization consultancy was undertaken to assess the current impact of diabetes mellitus in Oman. Routine national health statistics suggested that diabetes was the principal diagnosis in approximately 1% of all hospital discharges in 1988. The number of 'new cases' of diabetes treated at hospitals during the same year was 4.8 per 1000 Omani population, representing almost 6000 diabetic patients. In 1989, at the Royal Hospital, Muscat, diabetes was recorded as the principal diagnosis for 2.6% of all discharges, and 6% of those in subjects aged 45 years and over. It is known that the frequency of diabetes is generally underestimated by routine health statistics. Limited ad hoc investigation during the consultancy suggested that approximately 9% of all adult hospital admissions and 12% of adult hospital bed occupancy were associated with diabetes. Thus, diabetes should be considered a priority in a national health strategy for Oman. It is recommended that emphasis be placed upon epidemiological research, education, and the provision of appropriate technology.