Muscular activity of the oviductal isthmus was recorded in intact awake rabbits with an extraluminal optoelectronic transducer. Telemetered data were collected continuously during the periovulatory period to relate changes in contraction frequency to oviductal transport function. Mean frequencies during estrus ranged from 11.7 to 18.7 contractions/min. Animals stimulated to ovulate either by luteinizing hormone (LH) or by mating showed equivalent responses. Within 2 h following the stimulus, the frequency increased rapidly and remained elevated more than 50% above the estrous control level for approximately 10 h. Thereafter, the frequency declined slowly to reach a second plateau, 30% below the control level, which was maintained throughout the 2nd and 3rd poststimulus days. Subsequently, the activity returned to the prestimulus level. The periods of elevated and depressed activity correspond closely in time to the periods of rapid preovulatory transport of sperm and slow postovulatory transport of ova through the isthmus, suggesting the possibility of regulation of gamete transport by the oviductal musculature.