This study was undertaken to evaluate the presence and significance of pericardial effusions in postoperative open heart patients. One hundred consecutive patients received echocardiograms 7-10 days and 6 months following their procedure. Presence or absence of pericardial effusion was correlated with chest tube placement and number, and pericardial sac closure. Anticoagulation therapy and/or hematological disorders also were noted. This investigation currently lacks several patients for completion and results are pending data analysis.