;A group of 1,121 Lebanese males and females, 25–64 years of age, who were working full-time at the American University of Beirut, were screened for diabetes mellitus. A loading dose of 50 grams of glucose was used. Positive cases were investigated and followed up using glucose tolerance tests. A total of 37 diabetics were found, 19 cases were previously known and 18 were newly identified, for a prevalence rate of 3.3% in those tested, (1.7% known and 1.6% unidentified diabetics). Diabetics were compared with non-diabetics of the same age-group with regard to certain variables. No significant differences were found between the two groups as to place of residence, religion, occupation, salary, physical activity required in employment, the taking of regular physical exercise, and smoking habits. Significant differences were found with regard to overweight, symptoms of the disease and diabetes in other family members. Many newly identified cases reported symptoms of diabetes but were unaware of their significance. The need of screening for diabetes in developing countries is emphasized.