OBJECTIVES: The purpose of this study was to compare levels of parenting stress and efficacy in mothers of children suffering from attention-deficit hyperactivity disorder (ADHD) and internet addiction disorder (IAD), mothers of children with ADHD alone only, and those with normal children. METHODS: Participants were composed of 25 mothers of children with ADHD and IAD, 35 mothers of children with ADHD alone, and 50 mothers of normal children. They completed the Parenting Stress Index (PSI) and Parenting Sense of Competence (PSOC). RESULTS: In comparison with the mothers of normal children, the mothers of children with ADHD and IAD and the mothers of children with ADHD alone showed significantly higher levels of parenting stress and lower parenting efficacy. However, a comparison of mothers of children with ADHD and IAD with those of children with ADHD alone did not show any significant differences in their levels of parenting stress or efficacy. CONCLUSION: Mothers of children with ADHD, regardless of the presence of IAD exhibited a higher level of parenting stress and a lower level of parenting efficacy than mothers of normal children.