The aim of this study was to analyse the antibacterial Activity of Pittosporum viridiflorum leaves extract against laboratory strains of selected microorganisms. Infusions of the bark of P. viridiflorum are used to treat stomach complaints, chest pain, malaria and other fever. The mean zones of inhibition of the extract against microorganisms were 12.67±0.882 mm for Enterobacter aerogenes, 12.50±0.281mm for Escherichia coli, 11.67±0.333 mm for Proteus vulgaris, 11.67±0.000mm for Bacillus cereus and 7.67±0.333mm for Salmonella typhi. The penicillin positive control showed large zones of inhibition and the dimethylsulfoxide negative control did not show any zone of inhibition. This report suggests that the extract was active against all the other organisms except S. typhi because the zone of inhibitions was less than 8 mm. Analysis of variance showed that the zones of inhibition of the extract and antibiotic control against the microorganisms were significantly different (p<0.0001). The Tukey’s honestly test further showed both significant and non-significant comparisons between the extract and controls for various bacterial organisms. This study has shown that controlling the growth of microorganisms in vitro can be achieved by the ethanolic extract of P. viridiflorum.