The theory of Sampson that endometrial cells and fragments desquamated during the menstrual period are transported through fallopian tubes into the peritoneal cavity where they implant, proliferate and develop into endometriotic lesions is generally accepted. Accumulating data suggest that deficient immunity against retrograde endometrium during menstruation may be involved in the pathophysiology of endometriosis. Recent studies in women with endometriosis demonstrated functional changes in several immunologic components in the peritoneal fluid as well as in sera of those patients. Among others it was shown that a wild pattern of cytokines take part in events occurring during endometrial cells implantation, proliferation and forming of endometriotic lesions. One of them VEGF seems to play a very important role in neovascularisation and implantation of ectopic endometrial lesions. In present study we evaluated the concentrations of VEGF in serum of patients with endometriosis and showed negative correlation between AFS score and VEGF concentration in peritoneal endometriosis. Above results do not confirm former observations indicating the role of VEGF in endometriosis pathogenesis.