There are indicators useful to measure the grasp quality of prostheses, two of them are the force that can be reached, and the precision needed to grasp an object. It is important to evaluate force and precision in hand prostheses because these characteristics are directly related to its performance and to the activities that can be done with it. Nowadays, there are no available criteria to evaluate these two characteristics. Existing criteria can be applied only in particular situations and can be applied only to a few prosthetic devices to obtain a general evaluation. This paper presents a proposal for criteria able to evaluate precision and force in-hand prosthetic devices. These criteria have three main original characteristics: Each system in the prosthesis is evaluated individually; quantitative information about its performance is obtained; the criteria can be used for evaluating most of the existing prosthetic devices. In order to show the application and use of the criteria the evaluation of two devices is presented: CDMIT© and SmartHand©. Prosthesis evaluation results show that both prosthesis have some particular aspects that can be improved, and thus reach a higher force and better precision. Criteria presented in this paper serve for stablishing a framework useful for compare several prosthesis in various aspects.