Sonographic guidance with 41 punctures and 38 catheterizations was employed in 68 patients. The approach was either intercostal or subxiphoid. Most punctures were performed with a 1.4-mm-thick plastic-sheathed cannula after local anesthesia. Complications were observed in 7 patients. In one patient a catheter introduced with a movable core-type guidewire pierced the right ventricle wall with uneventful recovery after surgery. Intercostal drainage caused pleural pain in 2 patients, and in 2, leakage to the pleural space. Two patients with heart transplants had severe bradycardia and drop of blood pressure, one after needle drainage and the other during guidewire manipulation. Direct monitoring generally ensures a correct position of the instruments and hazards to adjacent organs can be avoided. In small effusions a simple needle aspiration with a plastic-sheathed cannula is safer than catheter drainage.