The thermal entrance problem for low Reynolds number, turbulent flow of gases in circular tubes is solved analytically by the method of Sparrow, Hallman, and Siegel. Fluid properties are considered constant. The solution is based on a Reynolds-number-dependent velocity profile developed, in a companion paper, by modifying Reichardt’s wall and middle law eddy diffusivity expressions. Tabular values of the eigenvalues and normalized Nusselt numbers are presented for a range of Reynolds numbers from 3,000 to 50,000. The axial variation of Nusselt number is found to be correlated by