From 1967 through 1984, single- or double-valve replacement for rheumatic heart disease (RHD) was undertaken in 184 children (aged 4 to 15 years) in Tunis. At the time of operation most patients were in an advanced state of cardiac disability, but most of them were still in sinus rhythm. A total of 222 valves were inserted. The most commonly used replacement valve was the Starr-Edwards caged-ball prosthesis, with 12 hospital deaths (6.5%). There were no hospital deaths among 19 children who had a (glutaraldehyde-treated porcine) xenograft replacement valve; however, a much higher rate of valve failure occurred later, owing to valve calcification (14 of 19 replacements, 11 requiring reoperation). There were 24 episodes of clinical thrombo-embolism in 21 children after insertion of a prosthetic valve, but only one in a child with a xenograft valve. Two thirds of the patients with prosthetic valves were on anticoagulants, but fewer than half of them had effective levels because of low compliance. For the group with prosthetic valves, the 10-year survival rate was 70%.