Serum prolactin level was estimated in 20 women with ovarian malignancy. High prolactin level was observed in 13 out of 20 women. However, no correlation was seen between prolactin level and the stage of the disease. Serial measurement of prolactin showed a correlation of prolactin level with tumor mass in three patients in which serial tumor mass volume measurements were available. A rise in serum prolactin level was observed in women who had recurrence of the disease. Although the current study is based on a relatively small number of patients, it may be concluded that serum prolactin level might be used as a tumor marker to monitor the therapeutic response in cases of ovarian malignancy.