Postpericardiotomy syndrome (PPS) is a frequent complication after cardiac surgery. In a recent study, elevated anticardiolipin antibody (ACLA) titres were observed in patients with PPS. The value of anti-heart muscle antibodies (AHA) for the diagnosis of PPS remains controversial. Therefore, a prospective double-blind study was performed to test the sensitivity and specificity of ACLA and AHA for the diagnosis of PPS. ACLA titres (ELISA) and AHA, elevated by immunofluorescence, the clinical course and routine laboratory parameters were assessed in 57 patients before and after elective cardiac surgery. ACLA increased and AHA first appeared after surgery in patients both with and without PPS. The sensitivities of a > or = 1.5-fold increase in IgM-ACLA titres, of a > or = 2-fold increase in IgG-ACLA titres and of the occurrence of AHA > or = 2+ for the diagnosis of PPS were 60%, 20% and 20%. The respective specificities were 43%, 79% and 85%. Thus, after cardiac surgery, increased ACLA titres and the occurrence of AHA, as assessed by immunofluorescence, may only contribute to the diagnosis of PPS to a limited extent.