Background: Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder, typically characterized by chronic mild inflammation, hyperandrogenism, insulin resistance, obesity, infertility, and anovulation. Emerging evidence indicates a potential mechanistic role of immune activation and acute phase proteins in the pathogenesis and progression of PCOS. Objectives: This study was designed to assess serum levels of neopterin with other selected acute phase proteins, namely, C-reactive protein (CRP), serum amyloid A (SAA), and fibrinogen in women with PCOS and their relationship with different PCOS phenotypes and inflammation activity.