Purpose: The purpose of this study was to evaluate the effect of different dentin deproteinization treatments on the microtensile bond strength (mu TBS) of composite resin to primary dentin affected by hypocalcified amelogenesis imperfecta (AI). Methods: Flat dentin surfaces were obtained from both extracted hypocolcified AI-affected and sound primary molars and then randomly allocated into three groups according to surface treatment (deproteinization with sodium hypochlorite [NaOCl], deproteinization with chlorine dioxide [ClO2], nontreoted controls). mu TBS of specimens were measured with a universal testing machine, and data were analyzed using one-way analysis of variance and Tukeys tests. Results: The mu TBS values for all groups with sound primary teeth were significantly higher than those of the comparable groups of hypocalcified AI-affected primary teeth (P<0.05). There were no statistically significant differences between the mu TBS values of the control and the NaOCl groups for either the hypocalcified AI-affected or sound primary teeth (P>0.05); however, the mu TBS values for the ClO2 groups were significantly higher than those of both the control and NaOCl groups (P<0.05). Conclusions: Within the limitations of this in vitro study, deproteinization with ClO2 can be considered effective in enhancing dentin bonding of hypocalcified AI-affected primary teeth.