Objective: To determine the effect of deproteinization on the success of composite crowns in hypocalcified amelogenesis imperfecta-affected permanent teeth in intraoral conditions. Method and Materials: A total of 32 permanent teeth in 4 healthy children with hypocalcified amelogenesis imperfecta were restored with strip crowns and composite resin. Teeth on the left side of the jaw were selected as the control group, and teeth on the right side of the jaw were selected as the treatment group. In the treatment group, a solution of 5% sodium hypochlorite was applied for 1 minute after acid conditioning of tooth surfaces. Clinical success was determined by USPHS modified Ryge criteria up to 36 months. Results: The deproteinization procedure had no effect on the anatomic form of the restorations. The cervical integrity of the restorations in both groups showed inferior results after 36 months compared to baseline. For both groups, no recurrence of caries was observed. Conclusion: The deproteinization had no significant effect on the success of the adhesive restorations; however, composite restorations were clinically successful in children affected by hypocalcified amelogenesis imperfecta in long-term follow-up. (Quintessence Int 2009; 40: 113-118)