BACKGROUND The purpose of the study was to evaluate the effect of haemorrhagic shock on the outcome of fracture healing. METHODS Forty-two male Wistar rats were randomly divided into a control group and a shock group. After producing a tibia fracture we induced shock by creating a blood loss of 12 ml/kg body weight. The rats were isovolumetrically resuscitated with a colloid volume solution. Blood flow was measured by laser Doppler flowmetry. Mechanical properties were tested by three-point bending after 4 weeks. RESULTS The blood flow of the shock group was characterised by no reduction in the distal region and in the soft tissue in the first 24 h, while the flow in the control group was reduced to 39% of the pre-fracture level. Biomechanical testing showed a better fracture healing outcome for the shock group than for the control group in failure load (31/11 N; P=0.06) and flexural rigidity (22,7/4,7 Nmm2; P=0.07). CONCLUSIONS In the shock group the restoration of vascularity in the distal region and in the soft tissue in the early healing stages, provoked by the isovolumic resuscitation, led to enhanced fracture healing. In addition, the results indicate that a fast blood supply may generate an improved initial healing process that results in an increased mechanical outcome of bone healing. In general, our findings underline the close interrelation between blood supply and successful fracture healing.