Aim: Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic infection characterized by fever and hemorrhage that is endemic to northeastern Turkey. This study aimed to examine the association between procalcitonin and venous blood gas parameters and clinical course and prognosis in patients with CCHF. Material and Methods: A total of 96 CCHF patients who were followed up in the infectious diseases department between March 2020 and September 2020 were included in the study. The patients’ routine laboratory tests, serum procalcitonin, and results of venous blood gas analysis were analyzed retrospectively. Results: There were statistically significant differences in serum platelet, aspartate transaminase, alanine transaminase, creatinine kinase, lactate dehydrogenase, potassium, Creactive protein, sedimentation, D-dimer, activated partial thromboplastin time, ferritin, procalcitonin and lactate levels, and platelet/lymphocyte ratio among the patients with mild, moderate and severe disease (p=0.017 for potassium, p=0.004 for D-dimer, and p<0.001 for rest of others). In receiver operating characteristic curve analysis of serum lactate for the differentiation of patients with severe disease and those with mild/moderate disease, the area under curve was 0.802 and a cut-off value of 1.9 mmol/L had 77.8% sensitivity and 76.9% specificity. For serum procalcitonin, the area under curve was 0.892 and a cut-off value of 0.61 ng/mL had 83.3% sensitivity and 89.7% specificity. Conclusion: Serum procalcitonin and lactate level may be useful and easily obtained parameters to guide the evaluation of clinical severity and follow-up in patients with CCHF.