10.22376/ijpbs.2019.10.1.p1-12 Volume 9 Issue 4 2018 (October - December) In the present study, phytochemical screening and antimicrobial activity of lessThan i greaterThan Pisonia grandis R.Br. lessThan /i greaterThan have been studied. The lessThan i greaterThan P. grandis lessThan /i greaterThan crude extracts were prepared by using different solvents (ethanol, methanol, acetone, chloroform and ethyl acetate).The phytochemical screening shows the presence of secondary metabolites such as alkaloids, phenols, sterol, flavonoids, diterpenes, cardiac glycosides, coumarins, tannins, steroids, terpenoids and saponin. Alkaloids, glycosides and terpenoids were absent in acetone, chloroform and ethyl acetate extract. Saponin was extracted in all solvent except Methanol. All phytoconstituents are present in ethanol extract. Antimicrobial activity was done against eight pathogenic bacteria [two are Gram positive ( lessThan i greaterThan Bacillus subtilis and Staphylococcus aureus) lessThan /i greaterThan and six are Gram negative ( lessThan i greaterThan E. coli, Proteus vulgaris, Pseudomonas aeruginosa lessThan /i greaterThan and lessThan i greaterThan Lactococcus lactis, Micrococcus and Serratia marcescens) lessThan /i greaterThan ].The antimicrobial activity was determined by Kirby–Bauer test and zone of inhibition was measured in cm. In all extract T lessThan sub greaterThan 1 lessThan /sub greaterThan shows high activity than T lessThan sub greaterThan 2 lessThan /sub greaterThan . Among all the extract, ethanol showed good antimicrobial activity against all tested organisms next followed by methanol extract. SUDHARAMESHWARI.K, SUGANYA.M1 AND SALINI.R Pisonia grandis, antimicrobial activity, pathogens, phytochemicals, bacteria. 213-220