Objective: The present review was undertaken to create the required utilization of oral glucose tolerance test in a developing country with a high prevalence of diabetes mellitus and its complications. Sources of data: This review is primarily based on available literature on local and international studies on oral glucose tolerance test Result: Pregnant and non- pregnant preparation; indications, contra indications and the diagnostic criteria for diabetes mellitus using oral glucose tolerance test was elucidated. Determinant for the usefulness or otherwise of oral glucose tolerance test for diagnosis of diabetes mellitus was also discussed Conclusion: Proper understanding of oral glucose tolerance test and teamwork of pathologist, physician, obstetrician, surgeon and pediatrician to face the challenges of diabetes mellitus and its unwanted complications is recommended Nigerian Journal of Clinical Practice Vol.6(1) 2003: 34-37