montreal classification (mc) succeeded vienna classification (vc) in the characterization of patients with crohn′s disease (cd). in order to evaluate the differences and potential advantages of the first regarding the last one and validate the mc through the longitudinal analysis of the phenotypic variation of this population, 122 crohn′s patients were retrospectively analyzed and classified according to both classifications. the evolution of both subgroups and the need for surgery was analysed. results showed that mc reclassified 6 patients in the criteria age at diagnosis (a), 4 in the criteria location (l) and 18 in the criteria behaviour (b). the disease location (l) remained stable. the behaviour (b) by the vc classification changed at 3 and 5 years. 41,8% of patients underwent major surgery. a higher association between the need for surgery and the group b3 of mc was identified. there were no statistically significant differences between the survival curves and sex, smoking and age at diagnosis. conclusion: the mc is more sensitive in the phenotypic evaluation of behaviour of cd, especially after exclusion of perianal disease from the category penetrating disease. the classification of cd by phenotypic pattern could possibly, in future, be applied to predict its natural history.