The aim of this study was to compare self-reported immediate post-vaccination pain and safety of Priorix versus RORVax in 4- to 6-year-old children receiving their second dose of MMR vaccine, using the Faces Pain Scale-Revised (FPS-R), a validated self-report pain scale recommended by the French National Accreditation Agency and Health Evaluation. A total of 620 children from 28 French pediatricians completed all study procedures. Immediate post-vaccination pain was reported by 17.8% of the subjects in Priorix group (N=309) and by 44.7% of the subjects in RORVax group (N=311) [OR=3.7; P<0.001]. Parents' pain scores correlated significantly with children's scores. The reduction of immediate pain incidence in Priorix group persisted over the 4 post-vaccination days. This study, using a validated self-assessment pain scale, confirmed previous data showing a significantly lower incidence of immediate post-vaccination pain with Priorix as compared to RORVax.