The aim of this work is to study phytochemicals and evaluate the antibacterial activity of aqueous and ethanolic extracts of Myrianthus holstii bark on three reference and five clinical strains derived from biological products. The results obtained show that the gives the best extraction yield. Chemical screening revealed the presence of polyphenols, alkaloids, flavonoids, saponosides, quinones, anthocyanins, tannins, terpenoids and sterols in both extracts. The results obtained show that the strains tested have a variable sensitivity for the two extracts and their concentrations. Diffusion and dilution methods on Muller-Hinton were used to evaluate the antibacterial activity of the extracts. The diameters of the inhibition zones are between 8 and 16 mm for the ethanolic extract starting from 25 mg/mL and between 8 and 12 mm for the aqueous extract at 50 mg/mL. The results revealed that these extracts have a dose-dependent antibacterial activity on the bacterial strains used. However, the 70% ethanolic extract has a better antibacterial potential on the strains compared with the aqueous extract, namely on S. aureus (CMI=3.12 mg/mL), E. coli ATCC (CMI=12.5 mg/mL) and S. aureus Meti-R (CMI=12.5 mg/mL). Also, this extract is bactericidal on all strains studied and its MIC ranges from 3.12 to 100 mg/mL after 24 and 48 hours of incubation. This study showed that extracts of Myrianthus holstii could be used in the treatment of infectious diseases.