The aim of this study was to determine the phytochemical composition and micrographic charac-teristics of the plants consumed by Okapia johnstoni. The results indicate that each plant species has characteristic microscopic elements for its identification. These plants are rich in phenolic acids, anthocyanins, flavonoids, anthraquinones, coumarins, terpenoids and iridoids. Alchornea cordifolia is richer in total polyphenols (198.53±3.39 mg GAE/g DM) followed respectively by Musanga cer-copioides (91.87±6.71 mg GAE/g DM), Macaranga spinosa (59.65±6.54 mg GAE/g DM), Ficus val-lis-choudae (46.37±2.43 mg GAE/g DM), Cola acuminata (38.83±4.04 mg GAE/g DM), Pycnanthus angolensis (31.96±3.45 mg GAE/g DM), Alstonia boonei (31.55±1.60 mg GAE/g DM) and Trilepisium madagascariensis (25.18±0.99 mg GAE/g DM). As for flavonoids, the highest content is obtained in T. madagascariensis followed respectively by A. boonei, Pycnanthus angolensis, Cola acuminata, M. spinosa, F. vallis-choudae, M. cercopioides and A. cordifolia. The difference in the content of secondary me-tabolites is justified by the fact that their expression in the plant is a function of both abiotic and biotic factors and the specificity of each plant species linked to its genetic make-up. The charac-terization of these chemical compounds is necessary for the formulation of herbal medicines for the management of Okapi ex situ or for human health. Also, the microscopic profiles of the leaves powder of the studied plant species provide relevant information, which may be helpful for the plant authentication and for quality control of raw material.