The thermoelastic stress analysis method is a non-contact technique which utilizes the thermoelastic qualities of hard tissues such as bones. It enables easy measurement and imaging of surface stress distributions. Using this approach, we performed stress analyses of human tibias in simulated loading conditions at various modes of varus valgus loading on the knee joint. In normal loading, the greatest stress image was obtained on the posterior aspect, indicating that the majority of the stress was concentrated in the posterior part of the tibia. The epiphysis of the proximal tibia, which consists predominantly of cancellous bone, showed tensile stress and the diaphysis which consists of compact bone showed compressive stress in every plane. These results indicate that the tensile stress in the epiphyseal surface indirectly reflects the impact-absorbing properties of cancellous bone. Also, results demonstrated that small changes in the alignment of the knee joint have a great influence on the stress pattern of the proximal tibia.