During the past few years we have monitored tissue pressure in patients treated with intramedullary nailing of tibial shaft fractures. A value of 30 mmHg has been used as the threshold for fasciotomy. The purpose of this study was to evaluate this practice. Sixty-three patients were included in the series. Forty-three fractures were closed, 18 grade I (Gustilo) and two grade II. Tissue pressure measurements were performed in 43 patients. Eighteen legs were treated with decompressive fasciotomy, three on clinical findings alone, and 15 after measurement of a pressure higher than 30 mmHg. This gives a fasciotomy rate of 29%. At follow-up two patients were dead. All fractures were healed, and there were no major complications such as deep infection, extensive muscle necrosis, paresis or short-foot syndrome. Three fasciotomized patients had significantly reduced muscle strength compared with the contralateral leg.