In a prospective study, 51 tibial shaft fractures with severe open or closed soft tissue damage were treated with a new, thin (8 mm or 9 mm) solid locking nail, inserted without reaming. At 6 months or more after trauma, 43 cases were reviewed. Fractures were classified according to Müller with six type A, 25 type B, and 12 type C fractures. In 13 cases there was group II (n = 8) or group III (n = 5) closed soft tissue damage (Tscherne). Of 30 open fractures, 16 were group OII, six were group OIIIA and eight were group OIIIB (Gustilo). Postoperative treatment in 42 of 44 cases was possible without additional cast or brace. Full weight bearing was achieved in 26 cases within 12 weeks, and in 42 cases within 26 weeks. In 43 cases, fracture healing occurred with a mean of 21.9 weeks (range 12-40 weeks). There was one case with valgus of 6 degrees and three cases with anterecurvatum deformities of 5 degrees to 10 degrees. In four cases there was an external rotation malalignment between 10 degrees and 20 degrees. In three cases we found an internal rotation deformity of 10 degrees to 20 degrees. Shortening between 0.5 and 1.0 cm was found in five cases, and in one case shortening was 1.5 cm. None of the patients had an osteomyelitis.