Phagocytic activity of macrophages isolated from peritoneal fluid (PF) was estimated using flow cytometry. Study group consists of 28 patients with endometriosis and 19 patients with benign noninflammatory tumour of adnex(is) served as reference group. Macrophages were processed in two ways: fresh cells were obtained from women with endometriosis (n = 7) and reference group (n = 10) and frozen cells derived from patients with endometriosis (n = 21) and reference group (n = 9). Phagocytic activity of macrophages was measured against opsonized and conjugated with FITC E. coli. It is worth to notify that phagocytosis was determined in PF environment in the study. Percentage of phagocytosing fresh macrophages did not differ (p = 0.05) between subjected groups of patients and was respectively 64.3% +/- 17.3% vs 49.0 +/- 4.0%. Phagocytic activity of frozen macrophages derived from patients with endometriosis was significantly higher (p < 0.02) in comparison to reference group (14.3 +/- 9.1% vs 5.2 +/- 2.8%).