Background: Children with attention-deficit hyperactivity disorder (ADHD) have severe impairment in their social functioning, and such literature from their sibling relations is limited. Sibling relations have several dimensions to them and a more detailed assessment into their impairment in ADHD is needed. We compared quality of sibling relations among ADHD sibling dyads and healthy controls. We also correlated the quality of sibling relations with severity of inattention and hyperactivity in ADHD. Materials and Methods: The present case–control study enrolled 30 cases of ADHD and 30 healthy controls from a child guidance clinic. The quality of their sibling relations was assessed by parent-rated version of the sibling relationship questionnaire (SRQ) on four domains of warmth, power struggle, conflict, and rivalry as well as their respective sub–domains. Their severity of inattention and hyperactivity was assessed using the Vanderbilt ADHD Diagnostic Parents Rating Scale (VADPRS). Results: ADHD sibling pairs had significantly lower warmth, prosocial behavior, affection, companionship, and competition as compared to their healthy counterparts. ADHD child was admired less by the sibling, and they were also seen to nurture each other less. The most significant difference was seen in affection (r = 0.59), followed by nurturance (r = 0.56). Intersibling conflict correlated positively with hyperactivity scores on VADPRS (ρ = 0.410, P = 0.04). Conclusions: Sibling relations are significantly affected in ADHD, with lower warmth and nurturance. Most significant impairment is noted in affection followed by nurturance. Intersibling conflict correlates significantly with severity of hyperactivity.