devitalisation of the excised segment by autoclaving, and reimplantation of the segment. We have studied the changes in temperature in the medullary cavity, the head, the medial condyle and lateral condyle of calf femora during autoclaving at 134°C in two different autoclaves. There were impressive differences of temperature at different sites. The most unfavourable position was the lateral condyle, which consists mainly of cancellous bone: a short programme of 11 minutes produced a lowest temperature in the series of only 45°C, which may not be sufficient to kill all tumour cells.