Even though much is known about individual risk factors for institutional violence, large variations in frequency between institutions still remain unexplained. Staff attitudes have been pointed out as a possible important and explaining factor. The Perception of Aggression Scale (POAS) is a newly developed attitude inventory assessing nurses' attitudes toward aggressive patients. The aims of this study are to evaluate the factor structure of the Swedish version of the POAS and to evaluate its discriminatory capacity in different groups of nurses. The shortened POAS was handed out to 357 nurses at 12 different psychiatric wards in Sweden. Responses were analysed with exploratory principal component factor analysis. The emerging factors were correlated in a rank-transformed multiple regression analysis to individual characteristics of each nurse. The factor analyses revealed exactly the same factor structure in this Swedish sample of nurses as in previous German and Dutch studies. When expanding the factor analysis, a three-factor solution emerged. It was also found that the factor "Aggression as a protective measure" was correlated to age and experience of aggression management training while the factor "Aggression as dysfunctional/undesirable phenomenon" was sensitive for gender. The shortened 12-item POAS contains three discrete dimensions and thus seems to be a solid tool for evaluating attitudes towards violence. Of special interest is the possibility that the factor "Aggression as a protective measure" could be sensitive to training. Further studies should correlate dimensions of staff attitudes to the occurrence of inpatient violence.