Abstract The objective of this study is to determine the antioxidant activity and phytochemical constituents of methanol extract of five medicinal plants. Preliminary phytochemical screening was determined using modified method of Harbone while quantitative phytochemical test was carried out using HPLC technique method of AOAC. Preliminary phytochemical screening revealed the presence of flavonoids, phenols alkaloids, tannins and saponinsin the extract of V. donniana, P. biglobosa, E. convoluvloide, F. gnaphalocarpa and S. occidentalis. Anthraquinones was present in P. biglobosa extract only. Quantitative phytochemical test revealed that E. convolvuloide extract (0.92 ± 0.10 % w/w) and (0.29 ± 0.05 % w/w) has high amount of flavonoids and phenols respectively. Alkaloids, tannins and anthraquinones were high in F. gnaphalocorpa (36.06 ± 1.17 mg/100), V. doniana (1.10 ± 0.02 mg/100) and P. biglobosa (0.09 ± 0.01 mg/ml) respectively. DPPH radical scavenging activity, ABTS radical scavenging activity, hydrogen peroxide radical scavenging activity and ferric reducing antioxidant power method was used for Antioxidant determination. The results were expressed as percentage inhibition and IC50 (where 50% concentration of the extract scavenged free radical). S. occidentalis extract (IC50: 41.80 µg/ml) and (IC50: 69.19 µg/ml) scavenged free radicals using DPPH and FRAP methods compared to other extract. F. gnaphalocarpa extract (IC50: 44.63 µg/ml) and E. convolvuloides extract (IC50: 72.77 µg/ml) scavenged free radicals using ABTS and hydrogen peroxide radical scavenging methods compared to compare to other extracts.