Local heat transfer measurements have been made on cylinders with length-to-diameter ratios varying from 3.80 to 6.50 under rotating condition with superimposed crossflow. Three-wire heat flux sensors have been used in conjunction with a slip-ring apparatus for making the measurements. The rotational speed varied from 25 to 1400 rpm. The maximum values of rotational and crossflow Reynolds numbers attained were 4.6 × 104 and 2.7 × 104, respectively. It was found that for the same Reynolds numbers, the average heat transfer rate under pure rotation was about 30% higher than that for pure crossflow. The results obtained also show that in combined flow conditions, the Nusselt number can be adequately correlated against a Reynolds number based on the resultant velocity. © 1995.