BACKGROUND The determination of natriuretic peptide levels in patients hospitalized for suspected acute heart failure is important for the confirmation of the diagnosis and for the prognosis. Changes in natriuretic peptide levels in response to therapy have a strong prognostic value. OBJECTIVE To decide whether repeated natriuretic peptide measurements for acute heart failure show changes that could influence the diagnosis and/or the prognosis. METHODS Prospective data collection was carried out of N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels on admission and within 12 hours in patients hospitalized for acute heart failure. Only the data of those patients were analyzed whose symptoms started within 24 hours prior to admission and were due to acute heart failure. RESULTS The 23 patients whose data we analyzed had an average age of 77.9 ± 8.3 years. Most of them had left ventricular systolic dysfunction with an average ejection fraction of 34.1 ± 3.9%. The time between the start of symptoms and the first measurement was 6.7 ± 2.2 hours, while the time until the repeated determination was 6.5 ± 2.2 hours after the first measurement. The median value of the NT-proBNP levels in the 6 hours control showed an increase from 5064 pg/mL to 8847 pg/mL (p<0.0005), which amounts to a 75 percent increase - mean hs-troponin T showed an increase from 46 ± 25 ng/L to 78 ± 51 ng/L (p<0.002). CONCLUSIONS A significant increase in NT-proBNP levels is to be expected in early repeated measurement after hospital admission. This fact could have diagnostic and prognostic consequences if validated in a larger patient population. Orv Hetil. 2018; 159(25): 1009-1012.