1. The frequency of variable degrees of ischaemia of soft tissue in closed tibial and fibular shaft fractures is emphasised. 2. Two cases with ischaemia of calf musculature are described. 3. A follow-up study of 100 cases of closed tibial shaft fractures is analysed; ten patients were found to be affected. 4. The anatomical and pathological changes are discussed. 5. A plea is made for early surgical exploration in cases manifesting signs of ischaemia.