Numerical predictions of three-dimensional turbulent flow and heat transfer are presented for a rotating two-pass smooth rectangular channel with channel aspect ratio of 2:1. The focus of this study is to investigate the effect of rotation, channel orientation and the sharp 180degrees turn on the flow and heat transfer distributions. Two channel orientations are studied: beta = 90degrees and beta = 135degrees. A multi-block Reynolds-averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure. The Reynolds number (Re) is fixed at 10,000 while the rotation number (Ro) is varied from 0 to 0.22. Two inlet coolant-to-wall density ratios Deltarho/rho are studied (0.115 and 0.22). The numerical results are compared with the experimental data for both stationary and rotating two-pass rectangular channels.