he aim of this study was to evaluate the immunolocalization of fibronectin during reparative dentinogenesis in rat teeth after pulp capping with mineral trioxide aggregate (MTA) or calcium hydroxide (Ca(OH)2). The pulps of 72 upper and lower first molar teeth from 18 male Wistar rats were experimentally exposed. The pulps were capped with MTA or (Ca(OH)2); final restoration followed with zinc oxide and eugenol cement. The animals were euthanized at, respectively, one, three, seven and fourteen days postoperatively. At day one, all groups showed varying degrees of inflammation, from mild to severe. There was no positive reaction for fibronectin at day one. After three days, a partial acute pulpitis was observed in the Ca(OH)2 group. There was less inflammation in the MTA group (p<0.05), and a layer of fibrin barrier was observed along the pulp walls of the MTA material. The layer of fibrodentin formation showed positive reaction for fibronectin. At seven days, the Ca(OH)2 group showed mild inflammation and demonstrated more immunostaining for fibronectin than the Ca(OH)2 group (p<0.05) at three days. Pulps capped with MTA at seven days showed thicker fibrin barrier formation than the MTA group at three days and more immunostaining for fibronectin in whole groups (p<0.05). At fourteen days, there was no positive reaction for fibronectin in either the MTA or Ca(OH)2 group. It seems MTA showed better biocompability properties with the dental pulp tissue, inducing the expression of reparative molecule fibronectin compared with Ca(OH)2. Therefore, MTA may be a better choice for pulp capping procedures.