The development of the otoendoscope has allowed assessment of the mastoid bowl following canal wall-up mastoid surgery via a minimally invasive stab incision. The technique is diagnosed, but also allows clearance of residual disease. Since 1991 all our second look surgery has been performed using the otoendoscope. In 43 patients, cholesteatoma was detected in 14 (32.6 %) of whom 11 had residual disease consisting of a keratin pearl that was removed via the stab incision. In only 3 cases was the original incision reopened to permit removal of recurrent disease. Preoperative CT scanning was ineffective in diagnosing residual or recurrent cholesteatoma being unable to differentiate between scar tissue and cholesteatoma. The sensitivity of scanning was poor (42.9 %) and its predictive value was only 28.4%. Now we routinely use the otoendoscope via a stab incision at second look surgery.