Myristica fragrans Houtt leaves contain secondary metabolites such as flavonoids, terpenoids and alkaloids, which have antibacterial properties. At the nanoscale, the particles have a bigger surface contact area, resulting in increased amounts and solubility of the active chemical. This leads to a stronger antibacterial activity. This study aims to examine the influence of several chitosan variations on particle size, antibacterial properties and the form of nanoparticles produced from Myristica fragrans leaves ethanol extract. Ethanol extract was analyzed using the UV-Vis spectrophotometric method to quantify total flavonoid content. Nanoparticles were synthesized using the ionic gelation technique with several ratios of chitosan and sodium tripolyphosphate, specifically 8:1, 10:1 and 12:1. Nanoparticles were analyzed with a Particle Size Analyzer (PSA) and Scanning Electron Microscopy (SEM). Agar diffusion test for bacteria germs using a paper backer. Myristica fragrans leaves ethanol extract was 50, 40 and 30 %, while nanoparticle extract was 5, 4 and 3 %. The overall flavonoid concentration in the QE/ethanol extract was 39.7252 ± 1.9596 mg. Antibacterial test results against Staphylococcus aureus and Escherichia coli bacteria and Myristica fragrans leaves extract limit inhibition area at 30 % (13.35 mm), 40 % (13.68 mm) and 50 % (13.93 mm) for Staphylococcus aureus and 30 (13.28), 40 (13.45) and 50 % (13.81 mm) for Escherichia coli. Myristica fragrans leaves extract chitosan nanoparticles included 3 (14.70), 4 (15.30) and 5 % (15.56 mm) for Staphylococcus aureus and 3 (14.60), 4 (14.65) and 5 % (15.05 mm) for Escherichia coli. Ionic gelation can create nanoparticles of Myristica fragrans leaves ethanol extract with chitosan and sodium tripolyphosphate. Myristica fragrans leaves nanoparticle ethanol extract exhibits better antibacterial activity than ethanol extract. Increasing chitosan concentration affects particle size. The ethanol extract of Myristica fragrans nanoparticle leaves showed slightly better antibacterial activity than the ethanol extract. HIGHLIGHTS Nanoparticles of extracts and extracts have proven excellent antibacterial activity against human pathogens through paper disc diffusion method. Antibacterial test results against Staphylococcus aureus and Escherichia coli bacteria and Myristica fragrans leaves extract limit inhibition area at 30 % (13.35 mm), 40 % (13.68 mm), and 50 % (13.93 mm) for Staphylococcus aureus and 30 % (13.28 mm), 40 % (13.45 mm), and 50 % (13.81 mm) for Escherichia coli. Myristica fragrans leaves extract chitosan nanoparticles included 3 % (14.70 mm), 4 % (15.30 mm), and 5 % (15.56 mm) for Staphylococcus aureus and 3 % (14.60 mm), 4 % (14.65 mm), and 5 % (15.05 mm) for Escherichia coli. The synthesized extract nanoparticles can be used against human pathogens acts as antibacterial drugs. GRAPHICAL ABSTRACT