OBJECTIVE: To evaluate the olfactory fossae depth according to the Keros classification and determine the incidence and degree of asymmetry in the height on computer tomography scan(CT Scan). MATERIAL AND METHOD: Cross sectional observational study was done on 200 CT scans of 3mm slice thickness in coronal plane. The results were classified according to their Keros classification. Any asymmetries in the ethmoid roof depth and fovea ethmoidalis configuration were examined. RESULTS: In present study, depth of olfactory fossa was measured and classified as per Keros classification.Majority of cases i.e. 137 (68.5%) were of type II, 52 (26%) were of type I, 3 (1.50%) were of type III. 8(4%) cases were having asymmetric ethmoid roof with different classification type on either side of crista galli. CONCLUSION: To minimize probable complications and to avoid major complications, anatomic variations, particularly in the base of the skull, should be properly understood