The patients were admitted for harvesting of stromal stem cells by bone marrow aspiration from the iliac bone. BMSSC were expanded in tissue cultures for three weeks to an average of 5 x 106 cells. After successful culture the non-union site underwent decortication and BMSSC added to synthetic bone substitute (different types) on one side of the fracture (medial or lateral) according to randomisation. The side of treatment was blinded to patient, surgeons and radiologist. Standard radiographs were taken and evaluated independently by three experienced musculoskeletal radiologists. The extent of callus formation on each side was recorded. In equivocal cases computerized tomography (CT) was also obtained.