Wire coil inserted tubes are important in engineering applications. The conjugate heat transfer and thermal stress, which is induced by temperature differences in the wire coil inserted tube sheet of heat transfer equipment, were studied numerically in the paper. Three different wire coil inserts, which have different pitches, are considered. The smooth tube is also considered for comparison. Uniform heat flux was applied from the external surface of the tube. Water has been used as fluid. The energy and governing flow equations were solved using a finite difference scheme. The finite element method (FEM) was used to compute the thermal stress fields. The effect of the different wire coils on the thermal stress has been discussed in terms of the results extracted from the FEM. It was found that the maximum thermal stresses ratio occurred in the case of p = 2d for 3 m/s mean water velocity. Some designs to reduce the thermal stress in the wire coiled tube sheet were suggested. (C) 2004 Elsevier Ltd. All rights reserved.