Objectives: The use of traditional medicine as a source of relief from illness is a long-lasting practice. This is because of the possible adverse effects associated with synthetic drugs. The investigation of more plants with antimicrobial activities has been fuelled by the increase of multidrug resistivity of most clinical isolates. Although the leaf of Millettia aboensis has shown antimicrobial potentials against some clinical isolates, there is no report against Streptococcus mutans and detection of the phytoconstituents present. Methods: Extraction was done according to the maceration process using methanol and further purification via liquid-liquid partitioning. The clinical samples used were cultured anaerobically and aerobically within 72 hr and 48 hr with the blood agar and brain heart infusion broth respectively. The isolates were identified using appropriate tests and methods. The fractions were further analysed for their Phyto-constituents with the help of High pressure liquid chromatography __ampersandsignndash; diode array (HPLC-DAD). Results: Methanol extraction using 50 g of plant material produced 12.72% wet weight, while the fractions using 90 g of methanol extract produced 30.38% for water, 20.57% for hexane, 6.65% for ethyl acetate, and 4.19% for butanol as percentage yield. The compounds detected from the fractions of the leaf extract of M. aboensis includes septicine - 1, cyclopenol - 2, psammaplin A - 3, 3-phenyl chromen-4-one - 4, hyperin - 5, rikuzenol - 6, hyperoside __ampersandsignndash; 7 and N N-dimethyl tryptophan methyl ester - 8. There was zero antimicrobial activity recorded at 6.25, 12.5, 25 and 50 mg/ml against Strep. mutans. Conclusion: The phytoconstituents present in the fractions are promising lead compounds for subsequent investigation in search of new bioactive agents.