Thirty children and adolescents aged 6-18 years, diagnosed with ADHD and trichotillomania, will receive MPH monotherapy treatment for a period of 12 weeks, targeting both ADHD and trichotillomania symptoms as rated by the ADHD- rating scale (ADHD-RS) and by the Massachusetts General Hospital Hair Pulling Scale and Clinical Global Impression-Severity (CGI) scale. The rating scales will be assessed at baseline and at the endpoint (after 12 weeks).The side effects will be monitored via weekly spontaneous self reports by each participant. All results will be expressed as mean ±SD. Student's paired t-test and ANOVA test will be used as appropriate.