The increasing use of plant-based medicines necessitates safety evaluations of all medicinal plants. This study evaluated the effects of mango (Mangifera indica) leaf extracts on albino rats (Rattus norvegicus). The phytochemistry of the plant’s extract was evaluated, followed by a determination of its acute toxicity using 24 rats. Thereafter, the chronic toxicity of the extract was determined using another set of 24 rats, separated into four groups of six rats each. Rats in group 1 (the control) were administered distilled water, while groups 2, 3, and 4 received daily doses of 1000, 2000, and 3000 mg kg-1 body weight, respectively. The rats’ body weights and reactions were monitored for 90 days before blood, liver, and kidney samples were collected for hematological and histopathological examinations. The phytochemistry revealed phenols, alkaloids, tannins, flavonoids, steroids, glycosides, and saponins. The acute toxicity test recorded no mortality at doses up to 5000 mg kg-1, and all the rats behaved normally, except for one that was sluggish. The chronic toxicity test revealed no significant (p>0.05) weight difference between the control and treated rats. The packed cell volume, hemoglobin, and red and white blood cells of the rats fed 2000 and 3000 mg were significantly altered (p0.05), while lymphocytes exhibited no significant alterations in any of the groups. The treated rats’ livers revealed dose-dependent necrosis, whereas their kidneys showed atrophy and epithelial cell degeneration. The results obtained suggest that a single dose of the plant’s extract is not harmful, but repeated high-concentration dosing for a long time may result in toxicity.