Electrical stimulation was applied to the follicular walls, capsules of corpora lutea, and pieces of atrophic ovaries obtained from 29 human ovaries. The quantitative analysis of contractile capacity in these ovarian strips was performed on the basis of stimulation-response relationships. Only with follicular walls and capsules of corpora lutea was the steep linear dose-response relationship similar to that shown by the uterine tube obtained by alternating current stimulation. The basal portions of mature follicular walls showed much more distinct responses to AC-stimulation than the apical portions. This difference further indicates a possible role of contractions by basal follicular walls in the process of follicular rupture at the apex in the human ovulation. The contractile elements of these ovarian strips were electronmicroscopically investigated with the strips which had shown contractions and confirmed to be smooth muscle cells in the ovary.