This paper explores the benefits organizations perceive that they have attained by their ISO 20000 service management system standard certification. The paper proposes a classification of benefits and tests the relationship between that classification and general satisfaction with the standard. The study is based on 105 responses to ISO-20000-certified organisations survey in Spain. After a descriptive analysis of the sample, a structural equation model is designed to test the hypotheses presented. According to the model, ISO 20000 benefits can be divided into those which are internal and those which are external. The variables that best define each type are identified. Moreover, those benefits are shown to be related to general satisfaction with ISO 20000 certification. The findings can be extended to other IT service management standards such as ITIL.