Background: Resorption of primary teeth and eruption of permanent teeth involves a complex series of changes. The cellular and histological changes occurring during the process of resorption vary stagewise. The knowledge of the changes occurring in the pulp of deciduous teeth would provide information about the resorptive process. Aim: To evaluate the histologic changes of the pulp of deciduous teeth related to different stages of physiologic root resorption. Study setting and design: To establish the cause and effect relationship, a contrived histologic study design was planned. Materials and methods: A total of 60 extracted deciduous incisors, canines, and molars were included in the study. The remaining root length (RRL) was determined based on the standardized photographs. The teeth were then grouped into three based on the percentage of RRL. The teeth were subjected to decalcification with 5% nitric acid, following which histological processing was performed. Statistical analysis: The present study being a qualitative study design, descriptively explains the histologic findings, and no statistical tests have been applied. Results: During the initial stages of resorption, there were no histological alterations noted in the pulp, particularly in the cervical 3rd, with the cellular structure relatively maintained. As the resorption progresses, reversal lines were evident, indicating a process of repair occurring simultaneously during the process of resorption. With further advancement, the repair is overtaken by the resorption indicated by the presence of resorptive cells. Neovascularization and an increase in immune cells are also evident in advanced stages. Conclusion: The pulp exhibits progressive changes as the resorption continues from stage I to stage III. The changes vary from a smaller number of immune cells and odontoclasts in stage I to increasing number of the same as resorption progresses.