The diagnosis and staging of acute cholecystitis, upon a lot of diagnostic methods and some scoring systems, is still a great clinical problem. The aim of the study was to investigate if serum Troponin I is elevated in patients with acute cholecystitis. Following informed consent, 65 patients with clinical and laboratory signs of acute cholecystitis were enrolled. All patients had measured serum Troponin I level and an abdominal ultrasound was done before definitive treatment was performed. Increased serum Troponin I level was found in most patients with severe form of acute cholecystitis (p < 0.00001). It reached sensitivity of 94.5% and specificity of 57.1% of this test. In multiple regression analysis Troponin I significantly correlated (p < 0.05) with the serum aspartate aminotransferase (r = 0.27), gamma-glutamyl transferase (r = 0.25) and gallbladder wall (> 6 mm) thickness (r = 0.58). Our study confirms that in most patients with severe and acute cholecystitis, serum Troponin I is increased. Troponin I level is in a lower range than it would be in patients with cardiac muscle damage or necrosis. Measuring serum Troponin I is a fast, reliable and widely performed test that could, with other routinely measured parameters, help in early diagnosis of the severe form of acute cholecystitis.