In this study, we aimed to evaluate the degree of inflammation in polycystic ovary syndrome (PCOS) phenotypes by comparing the monocyte-to- High-density lipoprotein (HDL) ratios showing inflammatory and oxidative stress among different phenotypes of PCOS. In this case-control study, we studied 186 women with PCOS and 59 age-matched healthy women. PCOS women were prospectively classified into four phenotypes based on NIH Expert Panel criteria. The degree of inflammation between the non-PCOS control group and four PCOS phenotypes was compared by measuring monocyte-to high-density lipoprotein ratio (MHR). The prevalence of phenotypes A, B, C and D were 29%, 22%, 26% and 23%, respectively. MHR was found to be the highest in phenotype A (13.7 +/- 4.9) among the PCOS phenotypes and the lowest level was found in phenotype D (9.0 +/- 1.9), which is the non-androgenic phenotype. MHR were significantly different across the four PCOS phenotypes; with the highest value were present with phenotype A. As an easily accessible simple marker, the monocyte/HDL ratio may be promising for detecting at-risk metabolic phenotypes in PCOS.IMPACT STATEMENT What is already known on this subject? Polycystic ovary syndrome (PCOS) is a syndrome that progresses with chronic inflammation and has long-term effects such as diabetes and cardiovascular risk. The inflammatory process in PCOS has been demonstrated by many parameters. What do the results of this study add? The level of inflammation among PCOS phenotypes in Turkish women was evaluated by the monocyte-to high-density lipoprotein ratio (MHR). Inflammatory cytokines have been studied extensively in the literature comparing PCOS and non-PCOS patients, but studies of inflammatory levels between PCOS phenotypes are rare. What are the implications of these findings for clinical practice and/or further research? Inflammatory status in PCOS is important in terms of disease severity and long-term complications. It is now important to apply a clinical approach, knowing that PCOS is no longer a single syndrome but a difference in phenotypes. In future studies, it is necessary to investigate the phenotypes of patients with PCOS with different inflammatory markers.