OBJECTIVE To investigate the clinical presentation and current management strategies of pericardial effusion in patients with malignancy. METHODS Retrospective single centre, consecutive observational study. METHODS University hospital. METHODS 93 consecutive patients with a past or present diagnosis of cancer and a pericardial effusion, including 50 with a pericardial effusion > 1 cm. RESULTS Of the 50 patients with pericardial effusions > 1 cm, most had stage 4 cancer (64%), were symptomatic at the time of presentation (74%), and had right atrial collapse (74%). Twenty patients were treated conservatively (without pericardiocentesis) and were less symptomatic (55% v 87%, P = 0.012), had smaller pericardial effusions (1.5 (0.4) v 1.8 (0.5), P = 0.02), and less frequent clinical (10% v 40%, P = 0.02) and echocardiographic evidence of tamponade (40% v 97%, P < 0.001) than the 30 patients treated invasively with initial pericardiocentesis (n = 29) or pericardial window placement (n = 1). Pericardial tamponade requiring repeat pericardiocentesis occurred in 18 (62%) of 29 patients after a median of 7 days. In contrast, only four (20%) of 20 patients in the conservative group progressed to frank clinical tamponade and required pericardiocentesis (P = 0.005 v invasive group). The overall median survival was 2 months with a survival rate at 48 months of 26%. Survival, duration of hospital stay, and hospital charges were similar with both strategies. By multivariable analysis, the absence of symptoms was the only independent predictor of long-term survival (relative hazards ratio = 3.2, P = 0.05). Survival was similar in the 43 patients with cancer and pericardial effusions of < or = 1 cm. CONCLUSIONS Asymptomatic patients with cancer and pericardial effusion can be managed conservatively with close follow up. In patients with symptoms or clinical cardiac tamponade, pericardiocentesis provides relief of symptoms but does not improve survival and has a high recurrence rate. Surgical pericardial windows or possibly percutaneous balloon pericardiotomy should be used for recurrences and should be considered for initial treatment.