The medicinal plants are widely used by the medical practitioners for curing various diseases in their day to day practice. Caesalpinia pulcherrima (Family: Fabaceae) is one of the most valuable medicinal shrub seen throughout tropical India.   The antibacterial activities of the hot and cold methanol extracts of the stems of Caesalpinia pulcherrima was evaluated on four bacterial strains like Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Proteus vulgaris. The invitro antibacterial activity of hot and cold methanol extracts was performed by cup plate agar diffusion method at different concentration of 10mg/ml to 50mg/ml using ciprofloxacin (ciprozol-500) in dimethyl sulphoxide as a standard drug for the comparison of antibacterial activity. From the experiment done the hot methanol extract of Caesalpinia pulcherrima did produce considerable antibacterial activity than the cold maceration extract was observed. The maximum antibacterial activity of hot and cold methanol extracts was exhibited against Bacillus subtilis when compared with standard drug. In addition the preliminary phytochemicals screening of the hot and cold methanol extracts of C.pulcherrima stems revealed the presence of alkaloids, carbohydrates, glycosides, saponins, tannins and steroids. The results obtained in the present study suggest that Caesalpinia pulcherrima stems can be used in treating diseases caused by the test organisms.