The antioxidant activities of Ocimum basilicum and Ocimum gratissimum consumed as spices in Nigeria were evaluated in a bid to provide better scientific basis for increased domestication efforts on them. Total phenol and flavonoid contents of the spice extracts ranged from 9.09 -27.41 µg GAE/mg and 5.38 -22.88 µg RE/mg respectively. The DPPH and hydroxyl radical scavenging activities of the spice extracts ranged from 58.43% -92.37% and 6.27% -16.67% respectively. The total antioxidant capacities and reducing powers of the extracts (measured as absorbance values) ranged from 0.137 -0.160 and 0.130 -0.158 respectively. Generally, Ocimum basilicum maintained superior antioxidant activities to O. gratissimum in all the test assays, and all the extracts showed dose-dependent antioxidant activities. Ascorbic acid, Gallic acid and Rutin used as reference compounds generally showed higher antioxidant activities to the spice extracts except in the hydroxyl radical scavenging assay. Put together, these results confirm that Ocimum basilicum and O. gratissimum extracts possess appreciable natural antioxidant potentials, thereby providing good justification for their increased domestication and consumption.