The process of rating information system successfulness in an organization means gathering grades with questionnaires on the importance and satisfaction of 46 information system successfulness factors from each and all functional areas, from users as well as from informationtechnologies specialists. Questionnaires should consist of two separate parts: one for grades of importance and other for grades of satisfaction. The first one gives the opportunity to information system management to assign priority corrective actions and to distribute resources of information system. For example, if one assumes that there are two unsatisfied factors of information system successfulness, successfulness IS-1 and successfulness IS-2, and that successfulness of IS-1 is ranked as more important than successfulness IS-2 (under the assumption that other factors are equal), first first it requires undertaking action and directing resources of the information system towards increasing thesatisfaction level of successfulness factor IS-1, and then successfulness IS-2. Similarly, if we have two factors of information system successfulness with the same importance and negative satisfaction, the factor with less satisfaction must be prioritized and receive more resources. The second gives to evaluator of information system successfulness the opportunity to identify individual unsatisfied factors of information system successfulness and to inform information system management.