Abstract : Nowadays, synthesis of plant based nanoparticles were gaining importance in the field of medicines for efficient drug delivery to cure many diseases. In the present study iron nanoparticles were synthesized with waste pista shell extracts and were subjected to various characterization studies such as UV-Vis spectrophotometer and FTIR. Antibacterial activity of Fe3O4-NP doped pista extract was anlysed by agar well diffusion method against E.coli, Pseudomonas aeruginosa, Bacillus subtlis and Staph