Nanopolymer-based delivery system is widely developed to enhance the solubility and bioavailability of drugs. One of them, Chitosan is a biocompatible, biodegradable and non toxic natural polymer. Other points, efavirenz is well known as a drug with low solubility in water and variable bioavailability less than 45 %. In this study, efavirenz was loaded into chitosan nanoparticle by ionotropic gelation method. Efavirenz-loaded chitosan nanoparticle (efavirenz-CNP) was prepared using low molecular weight chitosan (85 % deacetylated) and tripolyphosphate as a cross-linking agent. Efavirenz-CNP has particle size ±104 nm with Zeta potential value of -30.7 mV. As the results, the entrapment efficiency and loading capacity of efavirenz-CNP was 91.09 and 38.71 %, respectively. The in vitro drug release of efavirenz-CNP in buffer phosphate at pH of 7.4 reached 69.05 % for 24 h.