A critical step towards improvement of global health care delivery system lies in the discovery and optimal utilization of the wide range of medicinal plant resources available in nature. Against this backdrop, the antioxidant potential of two underutilized crops - Eremomastax speciosa (Hochst.) Cufod. and Eremomastax polysperma (Benth.) Dandy, growing under lowland humid tropical conditions of southern Nigeria were investigated using selected complementary in vitro assay systems. Ascorbic acid, Gallic acid and Na₂EDTA were used as standard reference compounds and the plants' leaves were extracted using 80% ethanol. Extracts of the two species contained good levels of antioxidant metabolites (36.44-57.56 µg Gallic Acid Equivalents/mg, and 67.83-141.58 µg Rutin Equivalents/mg for total phenol and flavonoid contents respectively). The extracts scavenged 50% (IC₅₀) of stable DPPH and hydroxyl radicals at 89.14 µ/ml and 40.76 µg/ml; 30.23 mg/ml and 23.18 mg/ml respectively. The extracts further chelated 50% of iron II ions (Fe²⁺) at 1.14 mg/ml and 1.21 mg/ml respectively. Results of the reducing power assay and total antioxidant capacity indicated that the extracts were potent in electron donation, thus were capable of reducing Fe³⁺ and Mo (VI) ions to their lower oxidation states. E. polysperma generally showed superiority (p<0.05) to E. speciosa in the entire test assays. The results obtained is a significant pointer to the potential health benefits of these underutilized plants to humans and animals as antioxidants that could provide natural mitigation to the hazardous effect of free radicals, hence the need to upgrade their medicinal value chain.