Pericardiocentesis guided by 2-dimensional echocardiography has been used at the Mayo Clinic since April 1980. The 2-dimensional examination localizes the pericardial fluid. Particular note is made of the place on the body wall closest to the fluid. An entry track that permits puncture of the pericardial sac without damage to any vital structure is then selected for the pericardiocentesis needle. Between April 1980 and March 1984, 132 consecutive pericardiocenteses in 117 patients were done by this technique. The volume of fluid obtained ranged from 75 to 1,700 ml (mean 650). Seventy percent of the taps were done for therapy, 21% for diagnosis, and 9% for both therapy and diagnosis. A Teflon-sheathed "intracath" needle was used to complete 80% of the pericardiocenteses. In the other 20%, a large catheter was secondarily introduced and connected to a closed drainage system. There were no deaths related to the procedure. One symptomatic pneumothorax occurred. There were 3 minor complications. Two-dimensional echocardiographic imaging of the heart and pericardial fluid permits a safe and effective means of performing pericardiocentesis.