BACKGROUND/AIMS Puumala virus causes nephropathia epidemica (NE), a milder form of hemorrhagic fever with renal syndrome that occurs in Central and Northern Europe. Several studies have sought to identify risk factors for severe NE. However, elevated procalcitonin (PCT) levels have not previously been investigated as a predictive marker for a severe course of NE. METHODS A cross-sectional prospective survey of 456 adults with serologically confirmed NE was performed. RESULTS PCT levels at the time of diagnosis were available for 43 out of 456 patients, and in 24 of these patients (56%) PCT levels were elevated ("PCT positive"). C-reactive protein (CRP) levels at admission to hospital and peak CRP levels during the acute course of the disease were higher in the PCT-positive compared with the PCT-negative group (p<0.05). Severe acute kidney injury (AKI) (RIFLE I and F) was present in similar numbers of PCT-positive and -negative patients (p=0.7), but antibiotics were more frequently used in the PCT-positive than the PCT-negative group (p<0.05). Within the PCT-positive group, PCT levels were similar among those receiving and not receiving antibiotics (p=0.13), and neither the duration of hospital stay nor CRP peak levels were lower in those treated with antibiotics (p=0.12 and p=0.13, respectively). CONCLUSIONS Elevated PCT levels are common in patients with acute NE. There was no association between PCT levels and severity of disease, including AKI or thrombocytopenia. It is important to distinguish Puumala virus infection from other causes of AKI with thrombocytopenia. However, PCT might not be useful in differentiating hantavirus infection from bacterial infection.