Background <p>Cannabis use disorder has been associated with a set of behavioral abnormalities and personality traits, including emotional dysregulation and impulsivity. In addition, cannabis use disorder is linked to changes in the function and volume of various parts of the brain, in particular, the hippocampus. This current study has investigated the relationship between cannabis dependence and emotional regulation, impulsivity, and the volume of brain reward system structures.</p> Methods <p>18 chronic cannabis users (Group A) and 23 healthy volunteers (Group B) were examined using the Structured Clinical Interview for DSM-5 Disorders, Emotion Regulation Questionnaire, Impulsive Behavior Scale–Short form (UPPS-P), and magnetic resonance imaging of the brain.</p> Results <p>Group A shows significantly higher scores of expressive suppression and UPPS-P subscales, and a significant negative association between expressive suppression and the lack of premeditation subscale of UPPS-P. A negative association was determined between cognitive reappraisal and the sensation-seeking subscale of UPPS-P. Sensation seeking showed a marginally significant negative correlation with the volume of the right nucleus accumbens (<i>P</i> = 0.044). Positive urgency showed a significant negative correlation with the volume of the left posterior insula (<i>P</i> = 0.002).</p> Conclusion <p>Cannabis dependence is associated with high impulsivity, which is correlated with an emotional dysregulation pattern. The volume of the hippocampus, the amygdala, and other brain reward system regions is reduced in cannabis use disorder and is correlated with the disturbance in impulsivity and in the emotional regulation process.</p>