Background and Purpose: Evaluating the personality of prisoners that have committed violent crimes, is a key factor in preventing and decreasing the incidence of delicts. Based on Persian Medicine (PM), brain temperament (Mizaj of brain) can play a critical role in reactions. The aim of this study was to assess the relationship between violent crimes and Mizaj of brain in order to help prevent crime.
 
Materials and Methods: This is a cross-sectional study that was conducted in Isfahan Central Prison in 2018. The brain Mizaj of criminal prisoners was assessed by a scientific form designed based on statements derived from PM resources. Collected data were analyzed by SPSS software (version 18).
 
Results: In this study, 143 participants were enrolled, the majority of which were 21- 40 years old. Analysis of data showed that the incidence of violent crimes is related to presence of hot and dry qualities in brain Mizaj.
 
Conclusion: Characteristics of imprisoned criminals in this study are compatible with findings of other researchers. Specifications of participants in this study are related to hot and dry qualities in brain Mizaj. Lifestyle modifications, along with other modern therapies, can be crucial in reducing the incidence of violent crimes.