© 2019Introduction: The aim of the study is to investigate the role of platelet count (PC) and mean platelet volume (MPV) in determining adenomyosis and endometriosis. Material and methods: This was a retrospective case control study that included adenomyosis, endometriosis and control groups. The adenomyosis group included 84 women diagnosed between January 2013 and January 2015 based on hysterectomy specimen. The endometriosis group included 102 patients underwent diagnostic laparoscopy and confirmed by histopathologic examination. Lastly, the control group included 88 women had no medical problem and underwent tubal ligation. Results: MPV (fl) was significantly lower in adenomyosis group (8.5) compared to endometriosis (9, p < 0.05) and control groups (9, p < 0.01). Modified platelet activity (MPV/PC) was significantly lower in adenomyosis group compared to control group (p < 0.01). Bivariate logistic regression model was used to assess the odds ratio of risk factors and serum markers related to endometriosis and adenomyosis. Variables showing significant differences based on post-hoc Bonferroni test were included in the logistic regression model for comparison of each disease with the control group. MPV was not found to be a risk factor both for presence of endometriosis and adenomyosis after adjusting for demographic and clinical characteristics. Discussion: Our study suggested that PC and MPV were not useful diagnostic markers for endometriosis or adenomyosis. Further research on how platelet indices and other inflammatory markers are related to inflammation might help better understand their potential as markers for these diseases.