The purpose of this study was to evaluate the transfer constant of conversion of plasma androstenedione to estrone ([p]AE1BU) as a function of total body weight and excess body weight in ovulatory and anovulatory young adult women. Twenty-four ovulatory and 31 anovulatory women were studied; their weights ranged from 90 to 350 pounds. The [p]AE1BU among these women ranged from 0.006 to 0.048. The extent of conversion of plasma androstenedione to estrone was significantly correlated with total body weight and with excessive body weight in both ovulatory and anovulatory young women. However, the mean [p]AE1BU for the anovulatory women (0.018) was not significantly different from that of the ovulatory women (0.015). Indeed, when the [p]AE1BU values of ovulatory and anovulatory women of similar total body weight or excessive body weight were compared, no difference was found in the extent of conversion of plasma androstenedione to estrone between the two groups.