This study was undertaken to find out the incidence of Open Angle Glaucoma (OAG) in the sibs and children of glaucoma patients and to determine the hereditary nature. An attempt was made to estimate the magnitude of risk of developing this disease in family of the affected patients. It was found from this study that out of 65 cases of adult family members with open angle glaucoma. 26.6% cases had positive hereditary history. Among 263 children and sibling of patients with known glaucoma 79 members had this disease and 14 new cases were detected. This findings demonstrate the need for adequate screening of the sibling and children of known cases of open angle glaucoma as they comprised high risk population. The risk was 10 times higher than that of general population.