Abstract: Using multi-beam interferometry, the cavitation experiment observation of elliptical roller-on-disc contacts was carried out under pure sliding conditions in a traditional optical EHL test rig. The results show that the shape and development of cavitation depended on the angle between the entrainment direction and the minor axis of the elliptical contact zone. Sheet cavitation presented itself when the entrainment speed and the applied load were met. For a constant applied load, increasing angle between the entrainment direction and the minor axis of the elliptical contact zone increased the entrainment speed when sheet cavitation appeared. Cavitation moved toward the contact center with the increase of the entrainment speed whereas the increase of the applied load was just the reverse. Cavitation moved along the entrainment direction with the increase of the angle between the entrainment direction and the minor axis of the elliptical contact zone and the position of cavitation depended on the entrainment speed quite markedly at the bigger angle.