These studies were designed to determine the preliminary oral toxicity profile of the crude aqueous stem bark extract of Musanga cecropioides (MCW) in adult Sprague-Dawley rats and its active chemical constituents by way of phytochemistry. The acute oral toxicity study was conducted using limit dose test of Up and Down Procedure according to the OECD/OCDE Test Guidelines on Acute Oral Toxicity (AOT425statPgm, version: 1.0) at a limit dose of 3,000 mg/kg body weight/oral route. Repeat dose oral toxicity studies were conducted by daily oral dosing of 750 mg/kg body weight of MCW dissolved in 1 ml of 0.9% saline and 1 ml of 0.9% saline to rats in the test and control groups, respectively, for 28 days. On day 29, blood samples for bioassays were collected by cardiac puncture under diethyl ether anesthesia. The phytochemical analysis was conducted using standard procedures. The LD(50) estimate of the extract was calculated to be greater than 3,000 mg/kg body weight/oral route. The extract caused a significant (P<0.05) decrease in weight gain, differential eosinophil count and increase in serum creatinine but did not affect the organ weights, other serum electrolytes (Na(+), K(+), HCO(3)(-)), liver enzymes and other hematological indices in test rats. Its phytochemical analysis showed it contains saponins, flavonoids, alkaloids, tannins, phlobatannins, glycosides, reducing sugars and anthraquinones. These results show that the aqueous extract of Musanga cecropioides is relatively safe toxicologically when administered orally. Thus, its use in folkloric medicine as an oral antihypertensive is relatively safe when used over the tested period.