Background and objectives: In this study, we compare portal vein Doppler ultrasound (US) findings between patients with Crimean-Congo hemorrhagic fever (CCHF) and healthy persons and investigate the practicability of these findings in the prediction of disease severity. Materials and Methods: In this prospective study, portal vein Doppler US was performed in patients diagnosed with CCHF and healthy persons between March 2016 and May 2018. The patients were grouped according to mild-to-moderate and severe progression of CCHF. Liver size, portal vein diameter, portal vein flow rate, spleen volume, and splenic vein diameter were recorded in the patients and healthy controls. Results: Of the 48 patients diagnosed with CCHF, 25 were male. According to the scoring made, 38 patients were evaluated as having mild-to-moderate disease progression, and 10 were evaluated as having severe disease progression. With respect to the Doppler US findings, liver size, spleen volume, portal vein diameter, splenic vein diameter, and portal vein flow rate were significantly higher in the patient group compared with the controls. However, no significant difference was found in these parameters between the severe and mild-to-moderate progression groups. Conclusions: In the evaluation of and follow-up with patients with CCHF, portal vein Doppler US is a non-invasive and reliable tool for diagnosis.