To evaluate the value of HRCT imaging in middle ear cholesteatoma, we prospectively analysed the CT images in 28 surgically proven cases with cholestatomas regarding main site of lesion, ossicular change, facial nerve exposure and fistula formation. The most common main site of lesion was the epitympanum (92.8%) The results of sensitivity, posistive predictability, and accuracy by CT imagings were as follows : for ossicular involvement 94.1% 88.8% and 86.2% in malleus, 96.0%, 88.8% and 85.7% in incus, 81.2%, 81.2% and 78.5% in stapes ; for facial nerve exposure, 66.6%, 57.1% and 81.2% for fistula formation 100%, 75.0% and 96.4% respectively. In conclusion, the temporal bone HRCT imaging is an accurate preoperative method in detecting main lesion site, ossicular involvement, fistula formation. Because of the low sensitivity and positive predictability in detecting facial nerve exposure, it is necessary to correlate the HRCT image with the clinical stantus.