Objective: Neopterin (NT) is a compound of low molecule-based pteridine. It is secreted by macrophages as a response to the stimulation of cytokines such as interferon-gamma, interferon-1 beta, tumor necrosis factor alpha or bacteria compounds such as lipopolysaccharides. Procalcitonin (PCT) levels may increase in the course of bacterial, parasitic, and fungal infections. Therefore, it can be used for the differential diagnosis of the infection, especially in cases of serious inflammation. In this study, the role of NT, and PCT in sepsis as a prognostic factor, and the relationship between the two parameters are examined.