Chitosan nanoparticles have attained more attention due to its potential applications in food, agriculture and pharmaceutics. Owing to its high biodegradability, and nontoxicity and antimicrobial properties, chitosan is widely-used as an antimicrobial agent either alone or blended with other natural polymers. The purpose of the experiment was to assess the antimicrobial bustle of chitosan based nanoparticles against few medical pathogens by using chitosan conjugated nanoparticles which are prepared based on the ionic gelation of chitosan extracted from the crab shell waste along with tripolyphosphate (TPP) anions. The chitosan nanoparticles characterization was confirmed by the diffraction study and spectral analysis. The size of the nanoparticle was identified using Transmission electron microscopy (TEM). The spectral studies showed a characteristics bands of –NH2 (amide) at 3450cm^-1 and carbonyl at 1629cm^-1. X-ray diffraction (XRD) patterns also indicated two characteristics crystalline peaks approximately at 20° and 35° (2q). The antibacterial activity of chitosan nanoparticles against medical important pathogens such as Escherichia coli, Staphylococcus aureus was estimated using minimum inhibitory concentration (MIC). The presence of primary amine groups in repeating units of chitosan grants reveals it several properties like antibacterial activity, antitumor activity.