OBJECTIVE: To examine the factor structure of the Portuguese version of State-Trait Anger Expression Inventory (STAXI) in clinical patients. METHOD: 400 subjects from an internal medicine outpatient unit and 200 from a medical ward were recruited. Patients answered questions about clinical data, the STAXI, and the Beck Depression Inventory (BDI). Raw score of the STAXI was submitted to reliability assessment and factor analysis. RESULTS: Internal consistency using the Cronbach's alpha coefficient was of 0.84. The STAXI significantly correlated with BDI at r=0.352 (p<0.01). The final solution of Principal Component Analysis identified five meaningful factors: Trait-Anger, State-Anger, Anger-Control, Anger-Out, and Anger-In. This structural model is close to the original theoretical construct of Spielberger's STAXI. CONCLUSION: The Portuguese version of STAXI presented an adequate factorial structure that permits the evaluation of anger dimensions among clinical patients.