Multiple valve replacement with pericardial xenografts (sizes 17 to 31) was undertaken in 76 patients. The incidence of early and late deaths was 10.5 and 3.9 per cent, respectively. ACtuarially it is predicted that 94.7 +/- 3.9 per cent of hospital survivors will be alive at three and a half years after valve replacement. Though long-term anticoagulants were not used, thrombotic valve obstruction was not seen in this series. A systemic embolus occurred early in one case only (0.95 episodes/100 patient years). Mechanical dysfunction of the pericardial xenograft has not been seen. Haemodynamic studies were performed in seven patients, eight to 21 months after valve replacement. The transvalvular gradients were negligible across the aortic pericardial xenografts. Gradients across mitral and tricuspid xenografts were small. The calculated surface areas ranged from 1.0 to 1.4 cm2 for aortic, 1.7 to 2.1 cm2 for mitral, and 2.0 to 2.4 cm2 for tricuspid valves. These results after multiple valve replacement are comparable to those reported with isolated mitral or aortic pericardial xenografts over a similar period of observation.