The level of tumor necrosis factor (TNF) in peritoneal (PF-TNF) of 74 women undergoing laparoscopy was determined. The difference between the mean concentration of PF-TNF of women with normal pelvic anatomy and women with moderate or severe endometrosis was significant (P < 0.01). The proportion of PF-TNF-positive women with PID and those with moderate or severe endometriosis was also significantly higher when compared to women with normal pelvic anatomy (P < 0.05; P < 0.02). The proportion of PF-TNF positive women among nulligravid and nulliparous women was significantly higher than that of women with two or more pregnancies (P < 0.01) and two or more deliveries (P < 0.005). These results indicate that the presence of PF-TNF is associated with primary infertility and endometriosis.