• To determine the working condition of otoscopes used in our community to diagnose middle-ear disease in children, we examined 221 otoscopes located in a hospital clinic, four emergency rooms, and the private offices of 96 physicians. The light output of each unit was measured in "as is" condition and then remeasured after a new lamp and, when possible, a new battery had been placed in the unit. A light output of 100 footcandles or more was judged optimal for clinical otoscopy. Replacement of the bulb was significantly more likely than replacement of the battery to restore adequate light output to those units with initially poor performance (80% vs 26%). Almost one third of physicians reported changing otoscope bulbs less often than every two years, and several did not know how to replace the bulb. Almost half of the 93 rechargeable nickelcadmium batteries inspected were outdated, but even these "expired" batteries provided adequate power when fully charged. Office otoscopes should be maintained properly to ensure optimal performance.