Shape Memory Alloy has been recently used for tissue fixation in minimal access surgery. The tissue closure is achieved by inserting the SMA fixator across the tissue join line. An electric current is then passed through the fixator which heats it and causes the fixator to its predefined shape. In design of the fixator, the main criterion has been to achieve full closure of the device while minimising collateral thermal damage to the surrounding tissue. Thermal analysis of the fixator and surrounding tissues has been conducted to predict the 3D spatial and temporal temperature distribution. Finite element method was used to model the heat transfer between the fixator and the surrounding tissue. The analysis results show that the heating effect within the tissues is confined to a layer of 1.0 mm thick next to the fixator.