Abstract Objectives To investigate whether there is an association between vascular endothelial growth factor (VEGF) levels in serum and peritoneal fluid, and the presence of pelvic endometriosis and its clinical symptoms. Methods Blood and peritoneal fluid sample levels of VEGF were measured in 46 women undergoing laparoscopy: 32 with suspected endometriosis and 14 with confirmed endometriosis. Data were analyzed according to phase of the menstrual cycle, symptoms, disease stage, and disease site. Results There were no significant associations between serum and peritoneal fluid levels of VEGF and the presence of endometriosis, even when controlling for the menstrual phase. However, among the women with confirmed endometriosis, there was a significant increase ( P = 0.002) in the mean peritoneal VEGF level in those in the late secretory phase compared with those in the proliferative and early secretory phases. Conclusions Measuring VEGF levels in symptomatic patients is not helpful to differentiate those with endometriosis from those with a different condition. However, in the late secretory and menstrual phases, mean VEGF levels were higher in women with confirmed endometriosis than in those suspected of having the disease.