Background/Aims: Puumala virus (PUUV) infection leads to nephropathia epidemica (NE), especially in endemic areas in Central Europe. The clinical course of NE is characterized by acute kidney injury (AKI) with thrombocytopenia followed by polyuria to a different degree. The prevalence of polyuria and its associated risk factors have not been reported in a large cohort of NE patients. Methods: Clinical and laboratory data during the acute phase of the disease were obtained from the medical reports and files of 335 patients who received in-hospital treatment during acute hantavirus infection. Comprehensive statistical models were developed to estimate the probability of polyuria. Results: The median age at diagnosis was 47 years (interquartile range, IQR 40-59) and 48% of the patients developed polyuria with a urinary output of 5,100 ml/day (IQR 4,200-7,300). The hospital stay was significantly longer in the polyuric group compared to the nonpolyuric group [8 days (IQR 6-10) vs. 6 days (IQR 5-8); p = 0.04]. Using logistic regression analysis, male gender (odds ratio, OR = 1.6; 95% confidence interval, CI 1.05-2.58; p = 0.03), oliguria/anuria during NE (OR = 2.56; 95% CI 1.65-4.01; p < 0.001), severe AKI (OR = 1.87; 95% CI 1.22-2.9; p < 0.001), and hematuria (OR = 1.78; 95% CI 1.02-3.15; p = 0.04) were significantly associated with the development of polyuria. In a multivariate model, the probability of polyuria was 0.19 (SEM ± 0.05) in female patients presenting with mild/moderate AKI without anuria/oliguria. Conclusions: Almost 50% of hospitalized NE patients developed polyuria, which was associated with a prolonged hospital stay. The probability of the development of polyuria was lowest in female patients with mild/moderate, non-oliguric/anuric AKI.