Wear of boundary lubricated spherical roller thrust bearings has been characterised qualitatively as well as quantitatively with 3-d surface measurements and 2-d form measurements respectively. Due to the curved contact surface in a spherical roller thrust bearing, the rollers will undergo sliding in the contact. For an unskewed roller there will be two points along each contact where the sliding velocity is zero. At all other points along the contact, sliding is present. The experimental results from the form measurements show that outside the zero-sliding points there is a significant change in surface profile due to wear. The results from 3-d surface measurements show that there are different wear mechanisms involved. Mild wear dominates at the start but for the long term tests, wear particles, presumably removed from the contacting surfaces, clearly influence the amount of wear.