The present study was carried out to investigate the flow characteristics through the curved section of a radiant tube which is used in the steel industry. The velocity profiles in the curved section were measured at a 1/2 scale water model apparatus by using 2D-LDV. The flow was also simulated numerically and a comparison was made with the experimental results. The flow was also simulated numerically and a comparison was made with the experimental results. The secondary flow in the curved section and the flow stagnation phenomena at the end of the curved section were confirmed. It was found that the swirl velocity component imparted by the burner degrades the uniformity of flow and enlarges the stagnant region in the curved section. This flow pattern is supposed to cause non-uniform heat transfer and the local failure at the end of the curved section.