The in vitro antimicrobial activities of the aqueous and ethanolic extracts of Tithonia diversifolia leaf, stem and root were studied. Two bacterial isolates (Escherichia coli and Salmonella typhi) and fungus (Candida albicans) were subjected to susceptibility testing using two treatment levels of the extracts (0.05 and 0.1 g/ml). Solvents (aqueous and ethanol) and two antibiotics (30 μg Ampicillin and 5 μg Ciprofloxacin) were included as negative and positive control respectively. The solvents did not show appreciable growth inhibition when compared to the extracts and reference drugs. The ethanolic extract showed higher growth inhibitory effect on all the test organisms when compared to the aqueous extract except for E. coli. Similarly, the root and leaf extracts showed better growth inhibition compared to the stem. The inhibitory effect was found to be dose dependant. E. coli was more susceptible to the extracts as indicated by the mean zone of inhibition which decreased from 31.10 ± 1.01 mm (100%) in the positive control (Ampicillin) to 25.00 ± 0.50 mm (80%) in ethanolic root extract and 22.50 ± 0.58 mm (75%) in aqueous leaf extract at 0.1 g/ml concentration. Both ethanolic and aqueous extracts of the various plant parts were found to be less effective on Salmonella typhi. This is indicated by low zone of inhibition which ranged between 0.00 ± 0.00 mm (0%)-13.50 ± 0.29 mm (41%). The ethanolic and aqueous root extracts at 0.1 g/ml showed better potency on Candida albicans with mean inhibitory zone of 27.50 ± 0.87 mm (72%) and 25.00 ± 0.29 mm (79%) respectively. These values compared well with reference drug Ciprofloxacin. The results indicate that T. diversifolia leaf and root could serve as good sources of antimicrobial agent