Abstract –Three groups of female Wistar rats were intravenously injected with the antineoplastic drug doxorubicin in a single dose of 5 mg/kg, 10 mg/kg and 20 mg/kg, respectively. The animals were killed 1 and 5 days after injection. Paraffin and Vestopal W embedded sections were prepared of the maxillary right and left incisors, respectively, and evaluated by light microscopy. Doxorubicin produced necrosis of single cells, of small groups of cells in the basal pulp and destroyed the preodontoblasts as evaluated 1 day after injection. On the 5th day of observation, the late preodontoblasts and basal pulp had regenerated, but the early preodontoblast zone remained absent, leading to an abnormal odontogenesis. This caused a marked reduction of dentin deposition in the apical part of the tooth and production of irregular predentin by cells in the pulp and by the young odontoblast