The aim of the present study is to investigate the growth of the tibia after femoral shaft fractures in children. We were able to follow up 44 patients (32 male and 12 female) after a mean of 8 years (range, 5 to 15 years). The age in the time of injury was 3 till 13 years (mean 7 years). The length of the femur, tibia and leg was measured on X-rays of the entire leg, and the measurements were compared with the contralateral side. A statistically significant number of tibial elongations were observed in fractures that had healed in considerable malalignment (at least 1 cm shortening, dislocation of at least a half of the breadth of the femoral shaft, angular deformity of more than 10 °) (p = 0.003) and in fractures that were subjected to manipulation (secondary reduction, change of treatment or traction weight) during the healing process (p = 0.007). Furthermore, all 7 patients who had infection requiring treatment at the tibial plateau extension had more pronounced tibial growth. No significant difference was found between tibial growth and the age of the child at the time of injury, the type of fracture, the location of fracture and the mode of treatment. The following factors were evaluated as being clinically relevant: primary, largely anatomic reduction, avoidance of secondary manipulation and prevention of infection at the tibial plateau extension.