A study was undertaken to estimate the histological changes of gingival enlargement induced by
Cyclosporin A (CsA) and Nifedipine, separately and in combination. Twelve adult rabbits were divided equally into four main groups. The first group received 10 mg/kg/day Nifedipine, the second received 10 mg/kg/day CsA, and the third received a combination of 10 mg/kg /day Nifedipine and CsA by gastric feeding. The fourth was regarded as a control group. Animals were given the drugs from day 1 of the experiment until day 70. They were then sacrificed for histological purposes. Results showed increase in the thickness of the epithelium with keratosis and acanthosis, and also increased vascularity. Collagen fibres and fibroblasts at different rates in the three histological groups were observed. Significant alveolar bone resorption with increased marrow spaces filled with fatty tissue were found in the CsA group. Non-significant changes in the alveolar bone of the Nifedipine group while subsequent bone resorption and bone deposition were seen in the combination group. These changes could be due to the effect of both drugs. Significant changes in the gingiva and the alveolar bone were shown in the three experimental groups compared with the control group.