Crimean-Congo hemorrhagic fever virus (CCHFV), a member of the genus Nairovirus of the family Bunyaviridae, causes a severe disease in humans with high mortality rates. In Turkey, the number of patients with CCHF has increased since 2002. Here, we aimed to treat CCHF patients with CCHFV hyperimmunoglobulin. We prepared a CCHFV hyperimmunoglobulin product from 22 individuals who survived CCHF infection. A total of 26 CCHF patients were enrolled into this study. For CCHFV hyperimmunoglobulin administration, a Kubar Unit (KU) was defined. As a standard therapeutic approach, 400 KU of hyperimmunoglobulin were given to each patient as a single dose before viral load was detected. We used one-step real-time reverse transcriptase-PCR to monitor the viral load of CCHF patients. According to the one-step real-time PCR results, 15 patients with a viral load of 10(8) copies/mL or more were defined as high risk. In this high-risk group, the survival rate was found to be 86.6% (13/15) and 2 patients died despite CCHFV hyperimmunoglobulin administration. CCHF is a very serious and highly fatal infection, particularly for patients in the defined high-risk group. Prompt administration of CCHFV hyperimmunoglobulin might be a very promising new treatment approach, especially for high-risk individuals.