The aim of this study was to compare the outcomes of pulpotomy of deciduous teeth in dogs with the use of formocresol, Gutta-percha, and mineral trioxide aggregate (MTA). In this experimental study, 24 deciduous premolar teeth, without internal and external resorption, in two hybrid Iranian dogs, aged 6-8 weeks, were divided into 3 groups, using a simple random technique. In the three study groups, diluted Buckley formocresol, Gutta-percha, and MTA were placed on canal orifi ces, respectively, and the crowns were restored with zinc oxide eugenol paste and glass ionomer. The teeth underwent a radiographic procedure and extracted after 1-month. The histological samples were evaluated in relation to infl ammatory reactions and formation of a hard tissue barrier. Data were analyzed with SPSS version 20 (SPSS Inc., Chicago IL, USA), using ANOVA, ANCOVA, Kruskal–Wallis test, and Spearman’s correlation coeffi cient (α = 0.05). Kruskal–Wallis test did not reveal any significant differences in clinical signs between the study groups at 2-week interval (P = 0.416) and clinical and radiographic signs 1-month after application of the materials (P = 0.503 and P = 0.122, respectively). ANCOVA did not reveal any signifi cant differences in grading between the groups over time (P = 0.927). There were no differences between materials in the clinical, radiographic, and histological outcomes.