Cholesteatoma is an expansive tissular process, non-neoplastic, well demarcated, developed in the temporal bone, with destructive effect. Cholesteatoma is diagnosed based on clinical, otoscopic examinations, sectional imaging examinations (computerized tomography in high resolution -HRCT and magnetic resonance imaging-MRI). Examination HRCT on the temporal bone is an exam with high sensitivity, important spatial resolution, it can detect small tissue damage, describes the local architecture, complications, but have low specificity, unable differentiate between tissue masses from different origins. MRI brings additional information, using conventional sequences in the preoperative evaluation about extension of the lesion, vascular complications but not in residual lesions or relapses. These new data are brought by using new type sequences Echo planar diffusion weighted. (DW-EPI) and non-Echo planar diffusion weighted (DW non-EPI), sequences that have high sensitivity and specificity even for small lesions (5 mm) with avoidance of a second-look surgery. This article aims to show cholesteatoma aspects, including the definition, history and etymology, classification, histology, clinical signs and the most important imagistic aspects.