A program is described here that analyzes the behaviour of roller-follower valve gear. The motion is computed from a kinematic analysis; the instantaneous radius of curvature and the pressure angle are determined, so that the contact force and stresses can be evaluated at the cam/follower interface. The validation of the software is discussed. Also analyzed, is the hydrodynamic lubrication of the roller-follower journal bearing. A case study is described in which journal and bearing wear are attributed to inappropriately sited oil feed holes. It is shown that there is a region where no hydrodynamic pressure develops, thus providing an appropriate location for the oil feed holes. The assumptions in the hydrodynamic analysis are discussed.