Objective: This research aims to evaluate the antibacterial activity and determine the chemical composition of the aqueous extract of the bark of Lannea barteri Engl. (DA) used in the traditional treatment of urinary tract infections in the Ivory Coast.Methods: The material is composed of DA, the bacterial strains of Pseudomonas aeruginosa and Acinetobacter baumannii, isolated from the urine of patients from different hospitals and subsequently stored. The qualitative analysis was performed using color-based detection tests and thin layer chromatography (TLC) reactions and the quantification of total phenols, flavonoids, flavone aglycones and anthocyanins using the method of Folin Ciocalteu. The method of diffusion on Mueller Hinton (MH) agar medium has been used for sensitivity tests. Results: The phytochemical screening of DA has revealed the presence of polyphenols, terpenes, and derivatives, coumarins, tannins, flavonoids, and alkaloids. Furthermore, the quantification of some polyphenols such as flavonoids, flavone aglycones, and anthocyanins was determined. The total polyphenols found was 0.757±0.003 mg/g MS representing respectively; 0.230±0.01 for flavonoids; 0.028±0.02 for flavone aglycones and 0.016±0.02 mg/g MS for anthocyanins. DA is bactericidal against Pseudomonas aeruginosa and Acinetobacter baumannii, which are mainly responsible for urinary tract infections.Conclusion: The bark of Lannea barteri Engl. (DA) is rich in flavonoids, flavone aglycones, and anthocyanins which are probably responsible for its antibacterial properties on Pseudomonas aeruginosa and Acinetobacter baumannii. This research thereby supports the use of this plant in the treatment of urinary tract infections.