The aim of this study was to determine the preliminary phytochemistry and antibacterial potentiality of hydro-ethanolic leaf extracts of Psidium guajava on Gram positive bacteria (Staphylococcus aureus, Coagulase negative Staphylococcus spp, Streptococcus pyogenes and Enterococcus faecalis) and Gram negative bacteria (Serratia marcescens, Pseudomonas aeruginosa, Escherichia coli. Proteus mirabilis, Klebsiella spp., Enterobacter spp and Citrobacter freundii) isolated from mid-stream urine of males and females between August and October, 2009 using standard microbiological and agar disc diffusion techniques. The results of the preliminary phytochemical constituents revealed that hydro-ethanolic leaf extracts of Psidium guajava contained secondary and primary metabolites such as saponins (++), alkaloids (++), tannins (++), cardiac-glycosides (±), terpenes (+), flavonoids (+) and sterols (+). The results also showed that both Gram positive and Gram negative bacteria were susceptible to hydro-ethanolic extracts of Psidium guajava at different graded concentrations (5 mg ml-1, 10 mg ml-1, 20 mg ml-1, 40 mg ml-1 and 80 mg ml-1) with the Mean ± SD zones of inhibition among the Gram positive bacteria ranging from 8.0 ± 1.5mm in Streptococcus pyogenes to 25.0 ± 3.0mm in Staphylococcus aureus while among the Gram negative bacteria, it ranged from 8.3 ± 0.5mm in E coli to 27.0± 3.0mm in Serratia marcescens. However, growth of Enterococcus faecalis was not inhibited by the tested leaf extracts at (5 mg mL-1). This depicts that the inhibitory activity was both organism and concentration dependent. The presence of the phytochemical constituents and inhibitory activities of hydro-ethanolic leaf extracts of Psidium guajava signify the potential of Psidium guajava as a source of therapeutic agents combating infections caused by common urinary tract pathogens.