The paper is focused on modelling claim frequency and extends the work of Kafková andKřivánková, 2014 (Kafková, S., Křivánková, L. 2014. Generalized linear models in vehicle insurance. Acta universitatis agriculturae et silviculturae mendelianae brunensis, 62(2): 383-388). We showed that overdispersion, nonlinear systematic component and interacted rating factors should be considered when the claim frequency is modelled. We detected overdispersion in the Poisson model and employed the negativebinomial model to show that considering heterogeneity over insurance policies yields better fi t of the model. We also analysed the linear eff ect of continuous rating factors and their mutual infl uences. We showed that non-linearity and interactions between rating factors yield the better fi t of the model, as well as new fi ndings related to the analysis of claim frequency. All empirical models were estimated on the insurance portfolio of Czech insurance company collected during the years 2004-2008.