The antimicrobial activities and phytochemical constituents of aqueous and hexane extracts of both the bark and roots of Dennettia tripetala F. Baker (Annonaceae) were determined using routine methods. Flavonoids, saponins, phenolic compounds, volatile oil, carbohydrate and reducing sugars were present in the aqueous extract of the root and bark, but absent in the hexane extracts. The antimicrobial activities of the extracts were tested against bacterial and fungal isolates using agar diffusion method.The commercial antibiotics used as positive reference standards to determine the sensitivity of the isolates were Gentamicin and Fluconazole.The aqueous extract of the root showed inhibitory activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa, with zones of inhibition ranging from 0.01mm to 30mm. The aqueous root extract inhibited the growth of Pseudomonas aeruginosa and Enterococcus faecalis with MIC values at 50 mg/ml.The results showed that the aqueous root extract possesed antimicrobial attributes as indicated by its activity on test bactetrial isolates. Phytochemicals were not present in the hexane extracts and the extracts showed no activity against the test organisms.