Introduction: The optic nerve is a direct continuation of the brain, surrounded by subarachnoid space. Measurement of the Optic Nerve Sheath Diameter (ONSD) provides indirect evidence of intracranial hypertension. Normative data in children in 1st decade is different from that of adults. This study provides age wise diameter of the optic nerve sheath from 0-80 years on T2 weighted MR images in a 1.5 Tesla MR scanner. The data serves as a baseline standard for comparison of ONSD in patients of various age groups. Objectives: To establish age and sex wise reference norms for ONSD from 0-80 years. Materials And Methods: This was a retrospective cross sectional study of analysis of MR image data set of 200 consecutive MRI studies of the brain, with normal optic nerves. A total of 400 optic nerve sheath diameters were measured (200 patients, both eyes). The study population was divided into 8 age groups of each decade of life from 0 to 80 years. The data was tabulated age and sex wise, for both the eyes and analyzed. Results: The mean diameter of the right optic nerve sheath was 4.48 mm with standard deviation of 0.69 (2 SD) and that of the left was 4.54mm with standard deviation of 0.71 (2 SD).Minimum diameter of the right and left optic nerve sheath was 2.98 mm and 2.80 mm respectively in a 14 month old male .Maximum diameter of the right and left optic nerve sheath was 5.5 mm and 5.4 mm respectively in a 16 years and 58 years old female. There was no statistically significant difference between the mean ONSD of the right and left nerves and between males and females. Conclusion: This study provides a baseline age wise ONSD and orbital diameter of general population. The maximum ONSD in any age group is never above 5.5 mm. If higher ONSD is found, the patient should be thoroughly investigated for intracranial hypertension.