This study serves to explore the chemical constituents of Azadirachta indica and Mangifera indica as a possible alternative sources of conventional antibiotics. Ethanolic extracts of Azadirachta indica and Mangifera indica stem bark were analysed for their chemical constituents. Phytochemical values for (Tannins, Oxalate, Phytate, Terpenoids, Trypsin inhibitor, Total Phenol, Total Carotenoids, Total Carotene Carotenes, Xanthophyll, Flavonoids, Alkaloids, Saponins and Antioxidant (DPPH Scanvenger) were revealed. The result were subjected to Studentized T-test as contained in SAS (1999). The result showed that all secondary metabolites analyzed were present in the bark of the two plant species studied but at different concentrations. The concentration of Tannin (1510.00 mg/kg), Oxalate (139.20 mg/kg), Phytate (15.55 mg/kg), Trypsin inhibitor (730.00 mg/kg), Flavonoids (78.50) and Saponins (17.71%) contents of Mango stem bark were found to be more than in Azadirachta indica. However, Azadirachta indica contained the highest Terpenoids (43.85 mg/kg), Total Phenol (34.00 mg/kg), Total Carotenoids (89.59 g/kg), Total Carotene Carotenes (69.88 g/kg), Xanthophyll (19.71 g/kg), Alkaloids (19.50%) and Antioxidant (68.65%) than the of M.I stem bark respectively. It can therefore be concluded that stem bark extracts, besides serving as good source of pharmacologically active phytochemicals may also be useful as supplements in human and animal nutrition particularly that the components are biodegradable compared to synthetic antibiotics
