Background & Aims: Complications and technical problems of paracentesis in cirrhotic patients are infrequent. However, the severity and the incidence of these events and their risk factors have not been assessed prospectively. Methods: Cirrhotic patients (n = 171) undergoing paracentesis were included. Of the 515 paracenteses, 8.8% were diagnostic, and 91.2% were therapeutic. Technical features, demographic data, and adverse events during a period of 72 hours after the procedure were examined. Results: Major complications occurred in 1.6% of procedures and included 5 bleedings and 3 infections, resulting in death in 2 cases. Major complications were associated with therapeutic but not diagnostic procedures and tended to be more prevalent in patients with low platelet count (<50 109/L), Child-Pugh stage C, and in alcoholic cirrhosis patients. Technical problems occurred in 5.6%. The most frequent complication was a leak of ascites at the puncture site (5.0%), and in 89.5% there were no complications. Conclusions: The safety of paracentesis in cirrhotic patients might be decreased if risk factors, which depend on the characteristics of the patient and of the procedure itself, are present. © 2009 AGA Institute.