Experiments were performed to determine heat-transfer coefficients both around the circumference and along the length of a heated tube situated downstream of a flow-splitting tee. The flow arrangement was such that air was delivered to the center port of the tee by a long unheated hydrodynamic development section and exited the tee via its two end ports. Identical heated tubes, each with its own flow control, were respectively attached to each exit port. One of the heated tubes served as a primary test section. The experiments were performed at several fixed primary test section Reynolds numbers and, at each Reynolds number, the flow through the secondary exit was varied systematically. The circumferential average heat-transfer coefficients in the thermal entrance region were found to be much larger than those for a conventional axisymmetric tube flow. Furthermore, the length of the thermal entrance region was substantially greater owing to the presence of the tee. Circumferential variations of the heat-transfer coefficient were confined to the initial portion of the entrance region, with circumferential uniformity being attained within about eight diameters from the center of the tee. At the first measurement station (two diameters from the center of the tee), the circumferential distributions exhibited deviations of up to 30% from the circumferential average.