Abstract: The cytological and toxicological potentials of an ethanol extract of a decoction used in South Western Nigeria for the management of breast tumors were evaluated using mice and Allium cepa models. The oral administration of the extract to the mice within the range of 400-1600 mg kg-1 b. wt., dosage did not result in any mortality until 2000 mg kg-1 body weight (b. wt.), when 60% mortality occurred. The LD50 of the extract administered intraperitoneally, was 400 mg kg-1 b. wt. Furthermore, the extract induced macroscopic and microscopic changes causing a dose-related root growth inhibition and chromosomal aberrations in Allium cepa. The effect of the extract was more pronounced at 1600 mg kg-1, dose while the EC50 was at 380 mg after 72 h. This decoction may present cytological and toxicological potential for managing breast tumors and corroborates its use in ethno medicine.