Twenty-eight children with femoral shaft fractures, treated with early spica cast, were evaluated with computed tomography (CT), for their femoral shaft rotational deformities. The femoral torsion angles were measured on both sides. If the torsion angle of the fractured side was more than the other side, it was considered as an internal rotational deformity and if it was less, it was considered as an external rotational deformity. Internal rotational deformities were detected in nine cases and external rotational deformities were detected in 17 cases. Rotational deformity was not observed in two cases. Four cases, with a rotational deformity more than 10degrees, were corrected with a gypsotomy through the level of the fracture. We concluded that a rotational deformity, which is an important complication in conservative treatment of the femoral shaft fractures in children, can be determined exactly with CT and corrections on the spica cast can be made with a gypsotomy. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.