Background: While the number of female criminals increases in Sweden, their care and eventual treatment still is mainly based on evidence from research with male interns. Studies shows that this group has an increased vulnerability, with high frequency of mental health problems.Aim: To investigate the effects of yoga on aggression, perceived levels of stress, attention and impulse control disorder of female prisoners.Method: Freely committing female inmates were randomized into two groups: (1) yoga group, where subjects participated in 90 minutes hatha yoga every week during a 10 weeks period, and (2) control group, where subjects participated in 90 minutes of physical activity every week during the same study period. A survey including self-rated instruments and the computerized performance test were completed by each participant before randomization and at the end of the 10 weeks study period.Results: The yoga group reported a decreased aggression and an attenuated level of stress, while the control group reported an increased level of perceived stress. In the computerized performance test an improvement in impulse control could be measured in the yoga group, while in the control group an increased prevalence of attention difficulties were detected.Conclusion: : There are strong indications that regular yoga exercise can contribute to decreased aggression, lower level of perceived stress and to increase control of impulsivity and attention. It may be a tool for individual-adjusted care to manage their mental health.