This study evaluated the effect of dosage on severity of cyclosporin-A (CSA) induced gingival overgrowth. Eighty (80) male Sprague-Dawley rats were randomly distributed into 4 groups. Rats in each group daily received CSA in mineral oil by gastric feeding at dosages of 0 (control), 3, 10, and 30 mg/kg, respectively, for 6 weeks. Stone models of the mandibular incisal region were obtained biweekly and were used for analysis of the gingival dimensions. Animals were sacrificed at the end of week 6 and tissue sections were processed for histopathologic evaluations. Animals were sacrificed at the end of week 6 and tissue sections were processed for histopathologic evaluation Gingival overgrowth including bucco-lingual and mesio-distal width and vertical height were significantly increased with increasing CSA dosage. Furthermore, the gingival dimensions displayed a positive linear relation to dosage and treatment duration. The histopathologic evaluation revealed a granulomatous tissue wedging the tooth-gingival interface in the 3 mg/kg group. This tissue had reached exuberant size in the 10 and 30 mg/kg groups. In summary, the analysis of gingival dimensions the histopathologic evaluation shows a dose-dependent effect on the severity of CSA-induced gingival overgrowth.