1. A method is described for studying pelvic blood flow in women by the indirect method of measuring vaginal temperature changes in response to a posture change. Ten women with chronic pelvic pain and venous congestion and 10 normal subjects were observed during posture changes over a 2 h period. 2. Vaginal temperature minus axillary temperature rose after subjects changed from the supine to the seated position, indicating a fall in the rate of pelvic blood flow. 3. A significantly greater variance in the rate of change in vaginal temperature minus axillary temperature was found in patients with pelvic venous congestion compared with control subjects ( P > 0.005). 4. The findings are consistent with a disorder of blood flow regulation in women with pelvic pain owing to congestion.