Introduction: In recent years, numerous studies have focused on the analysis of the primary mechanisms and forms of therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD). The analysis of such topics among similarly diagnosed young adults is only beginning to gain popularity. The present article attempts to answer the question of whether the level of individual temperament traits will predict an increase in the severity of ADHD symptoms in young adults.Materials and methods: The questionnaire study involved 111 young adults aged from 18 to 28 (M= 23; SD= 2.12; 70 women and 41 men). Fifty-one people were included in the clinical group, and sixty were qualified for the control one. The participants of the study completed a health questionnaire and a structured diagnostic interview on ADHD symptoms in adults (DIVA 2.0) and a questionnaire for the diagnosis of basic, biologically determined dimensions of human personality (FCZ-KT (R)).Results: The results indicate a significant role of four temperament traits that may be considered as specific risk factors for the aggravation of ADHD symptoms. These include briskness, rhythm, endurance and activity.Conclusions: In Strelau’s Regulatory Theory of Temperament, the variability of temperament traits (in the Polish population) is attributed in 44% to genetic factors. The remaining 56% indicate non-genetic factors. The obtained results may indicate which factors are important in therapeutic work both in the group of young adults with ADHD symptoms, and may also constitute a source of information for parents or teachers regarding younger children with these symptoms.