We have previously proposed the ovarian ERAANPS (endothelin-rein- angiotensin-atrial natriuretic peptide system). The present study was undertaken to examine in vivo the effects of herbal medicines [Tokishakuyakusan (TS), Keishibukuryogan (KB), Shakuyakukanzoto (SK) and Unkeito (UT)] on endothelin-1 (ET), renin and angiotensin II (A II) in the ovaries, of immature rats treated with 10 IU PMS for 48 h. ET and all components of renin-angiotensin system (RAS) were found at high levels in the ovary. Concomitant treatment with PMS plus TS, KB, SK or UT, especially TS and UT, tended to decrease the ET levels in ovary, while components of RAS tended to increase. However, ET, renin and A II levels in plasma were not at all affected after treatment with TS, KB, SK or UT. These results suggest that TS, KB, SK or UT may regulate the ovarian ERAANPS.