The reinforcement sensitivity theory of personality questionnaire (RST-PQ) is based on a theoretical analysis of the revised reinforcement sensitivity theory. Using a Swedish sample stratified by age and gender, the aim of this study was to test the six-factor structure of a Swedish version of the RST-PQ. Further, we examined the convergent and discriminant validity of the questionnaire. The results of the confirmatory factor analysis showed that the Swedish version did not fully provide support for the six-factor structure. An attempt to improve the model fit resulted in a significantly better model fit for a six-factor structure containing 52 items. Issues concerning the convergent validity were found, as indicated by all six factors having more than 50% of the variance due to error. The discriminant validity was satisfactory for all factors, except for goal-drive persistence and reward interest, which were highly correlated. This indicates a non-independence between these two factors in the model. Nevertheless, the RST-PQ has considerable promise and more emphasis should be put on investigating the convergent validity by using for example broader samples, stratified by country of origin, age, and gender.