Objective: Platelet count (PC) is higher in chronic inflammatory diseases. The aim of this study was to evaluate the PC in patients with severe pelvic endometriosis. Materials and Methods: Patients with advanced stage pelvic endometriosis were retrospectively evaluated in a tertiary center between January 2009 and December 2011. Patients with pelvic endometriosis were divided into two groups; advanced stage peritoneal endometriosis were classified as Group 1 (n = 28). Group 2 consisted of 29 patients which had ovarian endometrioma without clinically apparent peritoneal endometriosis foci. Group 3 included 51 women as control subjects. PC between the groups was tested by Student's t test. The mean values of three groups were analyzed by using one way ANOVA test followed post-hoc test Bonferroni. Results: PC in patients with pelvic endometriosis were found to be higher from the control group (290 +/- 67 10(9)/1; 264 63 +/- 109/1, respectively; p = 0.038). Patients with peritoneal endometriosis (Group 1) had significantly higher PCs compared with the healthy controls (309 +/- 65 109/1; 264 +/- 63 10(9)/1; respectively; p = 0.011). Conclusion: Increased PC in advanced stage pelvic endometriosis may be a sign of increased systemic inflammation. The systemic inflammation may be more apparent in advanced stage peritoneal endometriosis.