Local heat transfer and pressure drop were measured from the corrugated portion of the bottom wall of a rectangular channel where the opposite top wall took one of the three following constructions: (1) plane; (2) couered with corrugations making an in-phase arrangement with the bottom wall; (3) couered with corrugations making an out-of-phase arrangement with the bottom wall. There were a total of seven corrugations, and the corrugation geometry was sinusoidal. Measurements were performed for three different aspect ratios (corrugation height / channel height), and Reynolds numbers ranged from 22,000 to 52,000 in the turbulent region. Heated-coating liquid crystal technique was used for temperature measurements. The highest local Nusselt number was detected on the second corrugation regardless of Reynolds number, aspect ratio, or geometry. Higher Reynolds numbers and higher aspect ratios had similar effects, increasing local heal transfer coefficient. At the higher Reynolds numbers and with higher aspect ratios, two local minima were detected for the Nusselt numbers on each corrugation. Heat transfer results turned out almost the same whether the channel was couered with in-phase or out-of-phase corrugations; pressure drop was higher for the out-of-phase arrangements.