The dataset includes the quantitative data collected and results from statistical analyses conducted, for a research study on the anatomical investigation of the interthalamic adhesion in formalin-fixed adult human brains at the University of Pretoria. The sample was dissected and data collected from photographs of the region of interest analysed with ImageJ, a scientific image analysis application. Statistical analysis was conducted using the application SPSS. The data collected included prevalence, shape, location within the third ventricle, superior-inferior length, anterior-posterior length and surface area of the interthalamic adhesion, as well as surface area of the third ventricle.