This paper presents an assessment methodology to validate surgical simulators which will help researchers in avoiding most common errors by providing a complete structured guide. The methodology organizes the questions depending on the validities they are related to, helping in objectives' definition and consistent hypothesis formulation. We will define the study depending on its purpose, time course and the study factor assignment, taking into account legal and ethical issues and choosing the population and sample size. If it is an experimental study, we will determine if there exist a control group and the operational definition of variables. We will avoid extraneous variables and make our study blind, establishing the final evaluation procedure, and stipulating actuation and observation protocols. A feasibility study will be performed before executing the pilot and final studies in which we will analyse the data as indicated by the statistical plan, obtaining our results and conclusions. We provide an example, applying the assessment methodology step by step to the evaluation of a virtual reality arthroscopy simulator with haptic feedback. Finally, possible experiments are proposed as well as a conscientious study of different alternatives for the final evaluation procedure, and an extended proposal of surgical competence assessment measures. Copyright © 2009 John Wiley & Sons, Ltd.