Aim of the studyAim: The aim of this study was to assess the relationship between temperament and addiction to psychoactive substances in young adults.Subject or material and methodsMethods: 74 young adults participated in the study: 37 with substance use disorder and 37 controls, aged 18-28 years. They completed Rothbart’s Adult Temperament Questionnaire (ATQ) and a socio-demographic survey. The study was conducted in the Center for Treatment, Therapy and Rehabilitation, run by the MONAR Association.ResultsResults: Our results indicate significant differences between the test group and the control group in the following temperamental traits (p <0.05): Endogenous Sadness, Visual Discomfort, Inhibitory Control, Attentional Shifting, Sociability and Intense Environmental Pleasure. Compared to controls, persons with substance use disorder scored higher on endogenous sadness and intense environmental pleasure. Greater endogenous sadness suggests they experience more negative emotions and lower mood as a result of disappointment or loss, which promotes development of addiction.DiscussionDiscussion: This study demonstrates differences in the severity of some temperamental traits between persons with substance use disorder and control group.ConclusionsIt is suggesting that temperament can be a risk factor for addiction to psychoactive substances.