Background: The morphology of foramen magnum has a critical role in posterior cranial fossa pathologies and craniovertebral junction disorders. Foramen magnum is of considerable clinical interest as the vital structures traversing it are compromised in several pathologies affecting the posterior cranial fossa. Aim: The objective of the study is to assess the morphometry of foramen magnum and to determine the antero-posterior diameter, transverse diameter of the foramen magnum and the foramen magnum index. Material and Methods: The study was conducted on the foramen magna of 200 dry human skulls that were obtained from the Department of Anatomy of a private medical institutions.Skulls with intact foramen magnum were included in the study. The skulls which had partially missing or broken foramen magnum were excluded from the study. The anteroposterior and transverse diameters of foramen magnum were measured with a vernier calipers. The foramen magnum index was calculated. The shape of the foramen magnum was also noted. Results: The mean antero-posterior and transverse diameter of the foramen magnum was recorded as 33.27 ± 2.1 mm and 27.13 ± 2.4 mm respectively. The average foramen magnum index was observed as 1.2 ± 0.14.The sagittal diameter ranges from the minimum value of 31 mm to maximum value of 38 mm. The transverse diameter ranges from the minimum value of 26 mm to the maximum of 34 mm. The most common shape of foramen magnum observed in our study is oval(30%), followed by egg shaped (21%), round (19%), irregular (13%) and hexagonal (11%). Conclusion: The present study provides the mean dimensions of foramen magnum in South Indian population which may be used as reference in analyzing the morphological anatomy of posterior cranial fossa.