Closed intramedullary nailing is a successful method of treating adult femoral shaft fractures. In comminuted or segmental fractures, this operation is associated with an incidence of rotational malalignment and malunion. After locked nailing, this can only be corrected by further operation. A simple method of judging and obtaining rotational alignment in such cases intra-operatively is described. A comparison of two groups of patients with such fractures, one using this technique and the other using conventional methods of judging alignment, revealed statistically significant improvement in rotational alignment (p = 0.016).