The electric activity of the ovary was studied in 13 female mongrel dogs aiming at characterizing a normal electro-oophorogram (EOOG). Two monopolar silver-silver chloride electrodes were sutured under anesthesia to the ovary of the bitches which were in the anestrus phase of the estrous cycle. A daily recording session of 60 min was performed for 10 days. Furthermore, the effect of ovarian vessels' clamping, of oophorectomy and of ovarian insult by irradiation on the electric activity, was studied. Electric waves were recorded from the two electrodes. Each wave consisted of a negative followed by a positive deflection with a mean amplitude of 52.6 +/- 10.7 microV and frequency of 9.2 +/- 1.6 cycles per second. The waves showed the same amplitude and frequency from the two electrodes and were reproducible when the test was repeated in the same animal. Fast activity spikes were not encountered. Temporary clamping of the ovarian vessels caused diminution of the normal ovarian electric activity which returned to the preclamping state after clamp release. A 'silent' EOOG was obtained after oophorectomy. Two EOOG patterns were recorded from the irradiated ovary: silent and dysrhythmic. To conclude, an EOOG could be characterized for the bitches in the anestrus phase which is a quiescent phase of the estrous cycle. Further studies are required to record the EOOG in the other phases of the estrous cycle and in the various pathologic conditions of the ovary.