OBJECTIVE Minimised perfusion circuits (MPCs) are expected to reduce the side effects of conventional cardiopulmonary bypass (CCPB); however, conclusive data from sufficiently powered clinical trials are lacking. The purpose of this study was to evaluate the safety and efficacy of the ROCsafeRX minimised perfusion circuit. METHODS A randomised, controlled, multicentre clinical trial comparing both perfusion circuits in patients subjected to elective coronary artery bypass and/or aortic valve replacement is described. The primary end points of safety, defined as procedure success without device-related complications, and secondary end point of efficacy, including reduction of transfusion requirement and incidence of atrial fibrillation, are analysed. RESULTS To date, 291 patients have been enrolled and randomised (146 MPC vs 145 CCPB). With the exception of a significantly higher male population in the MPC group (83.6% vs 71.0%, p=0.01), both groups were well matched for demographic data and type of surgery. There were no device-related complications but a hard-shell reservoir had to be integrated in one MPC because of a tear in the right atrium that was managed uneventfully. Total transfusion requirement (329+/-599 ml vs 783+/-1638 ml, p < or = 0.001) and erythrocyte transfusion (181+/-341 ml vs 434+/-798 ml, p < or = 0.001) were significantly reduced in the MPC group. The incidence of atrial fibrillation was significantly lower in the MPC group (7.1% vs 19.5%, p < or = 0.01), while freedom of major adverse events showed no significant difference. CONCLUSIONS Lack of device-related complications combined with a significant reduction in postoperative atrial fibrillation and transfusion requirements have shown the ROCsafeRX MPC to be both safe and efficient for large-scale use in cardiac patients. Additional data are expected to confirm these initial findings.