Aim:An interthalamic adhesion (ITA) is a midplane rod-like neuroanatomical mass connecting two thalami over the cavity of the third ventricle. It is present in approximately 70-80% of healthy humans. The absence of an ITA has been considered as a midline defect of the brain associated with schizophrenia. The aim of the present study was to determine the prevalence, location, and dimensions of ITAs in Indian brains.Material and Methods:We examined 100 brains (50 cadaveric and 50 MR images) in the midsagittal plane for the presence or absence of ITAs, their location in the lateral wall of the third ventricle, and dimensions.Results:ITA found in 87 brains (87%), four showed duplication (4%). Both its duplication and absence were more frequent among male. It was most commonly located in the anterosuperior quadrant with posterosuperior extension. The mean of horizontal diameter (7.13±4.31 mm) was longer than the vertical (5.13 ±3.17) in all the brains. Its average area (37.98±41.47 mm2) showed huge variation (ranges between 4.40 mm2 to 203 mm2) and was significantly higher in females (61.23±56.22 mm2) than males (36.44±43.21 mm2) (p = 0.026). No correlation was found between the surface area of the ITA and the length of the third ventricle.Conclusion:Absence and duplication of ITA are fairly common in Indian brains with significant male predominance. Morphometric data are robust to advocate for the presence of sex differences in the ITA size, although not associated with surrounding thalamic or third ventricle anatomy.