['Bacterial infections are life-threatening complications in cirrhosis and early diagnosis is mandatory. Procalcitonin, a 116 amino acid propeptide of calcitonin, is an early marker of infection. The aim was to evaluate prospectively procalcitonin in the diagnosis of bacterial infection in cirrhosis. 127 patients with liver cirrhosis were analysed and stratified into three groups according bacteriological and morphological findings; decompensated patients with (group I = 36) and without (group II = 64) infection, and 27 non-decompensated and non-infected (group III).', 'Diagnosis of infection was made using standard criteria. Serum procalcitonin, tumour necrosis factor alpha, interleukin-6 and C-reactive protein were measured using commercially available methods.', 'PCT serum levels were significantly different between group I (2.8 ng/ml [0.4 - 20.4]), group II (0.6 ng/ml [0.1 - 5.9]) and group III (0.4 ng/ml [0.1 - 1.2]), respectively. Levels above 0.58 ng/ml had a sensitivity of 92 % and specificity of 78 % for the diagnosis of infection and were associated with a 50 % mortality in the first two months. Interleukin-6, tumour necrosis factor alpha and C-reactive protein were less sensitive and specific for the diagnosis of infection.'] Is procalcitonin a valid marker of infection in decompensated cirrhosis?