Sixty-six cases of acute compartment syndrome were treated by fasciotomy in forty-six extremities of forty-four patients. Fasciotomy performed early, that is, less than twelve hours after the onset of the compartment syndrome, resulted in normal function in 68 per cent of the extremities. Only 8 per cent of those having late fasciotomy had normal function. The complication rates for the early and late fasciotomized extremities were 4.5 per cent and 54 per cent, respectively. No significant differences in residual function or complication rate were noted with "open" or "closed" fasciotomy.