The effect of angled rib turbulators on the heat transfer of an orthogonally rotating square duct were experimentally investigated. The Reynolds and rotation numbers were varied in 10,000-20,000 and 0-0.08, respectively. The leading and trailing walls were rib-roughened with angles of 90 degrees and 60 degrees. The results showed that the rotation induced a peripheral variation of the heat transfer and the higher heat transfer was seen using the 60 degrees angled rib; judging from the local heat transfer variation, the skewed secondary flow induced by the angled rib seemed to result in additional heat transfer enhancement.