During its rich history, various evaluation models have been proposed in the field of evaluation of information systems (IS) success. The reasons for that can be found in the diversity of use of the IS and the multitude of stakeholders, that do not have a common view of the success of an IS. Three main aspects of evaluation of IS have been recognized social, managerial and technological. In this thesis a model designed especially for the evaluation of adequacy of ERP systems is proposed. The proposed model provides the evaluation of individual functionalities from three aspects, which is not the usual practice of existing models that only consider system as a whole. The model enables easy identification of critical functionalities, making it easier to formulate recommendations. The model has been tested on a case of Slovenian company. The results confirmed the reasonableness of evaluation of the individual functionalities as well as the evaluation from three different aspects.