The fatiguability of the acoustic stapedius muscle reflex in an actual noisy industrial environment was investigated in normal-hearing subjects. In a laboratory situation a small depression was found with a considerable individual variability. The stapedius reflex recovered slowly, approximately as a linear function of time. In a field study on an entire day of exposure in a ship-building yard the reflex depression was on the average 4 dB in response to a stimulation of 2000 Hz 10 min after the end of the workday. This corresponds to less than 8 dB immediately at the end of the exposure.