The purpose of this study was to see if relaxation at three different periods of a women's menstrual cycle would influence the duration of the cycle and day of ovulation. Students between the ages of 18-30 who were determined to have regular cycles based upon two months of record keeping, were given three relaxation sessions at different times from the start of menses, 12 during days 3, 4, and 5, 10 during days 8, 9, and 10 and 12 during days 19, 20, and 21. All participant were measured for the galvanic skin response (GSR) during a 20 minute relaxation session, 5 minutes baseline followed by 5 minute relaxation instructions and 10 minutes of music during which they were given biofeedback as to the GSR response. The GSR of 6 additional participants was measured with the relaxation manipulation 3 on days 3, 4 and 5 and 3 on days 19, 20, and 21. The findings are as follows: (1) Relaxation was most effective as measured by the GSR on days 19, 20 and 21, an important finding if one is interested in the effects of relaxation. (2) Greater relaxation as measured by the GSR within the session appeared to be effective in lengthening the start of the next menses; decreased relaxation appeared shorten the cycle. Findings were inconclusive regarding day of ovulation. This study is of importance in considering the therapeutic biofeedback treatment plans for women.