An experimental investigation has been conducted to clarify forced convection heat transfer characteristic and flow behavior of an isothermal cam shaped tube in cross flow. The range of angle of attack and Reynolds number based on an equivalent circular tube are within 0 degrees < alpha < 180 degrees and 1.5 x 10(4) < Re-eq < 2.7 x 10(4), respectively. The results show that the mean heat transfer coefficient is a maximum at about alpha = 90 degrees over the whole range of the Reynolds numbers. It is found that thermal hydraulic performance of the cam shaped tube is larger than that of a circular tube with the same surface area except for a = 90 degrees and 120 degrees. Furthermore, the effect of the diameter of the cam shaped tube upon the thermal hydraulic performance is discussed. (C) 2006 Published by Elsevier Ltd.