Gelatin (Type A) nanoparticles were prepared by a single W/O emulsion technique and characterized by infrared (IR) spectra, scanning electron microscopy (SEM), and particle size analysis. The IR spectra clearly confirmed the presence of gelatin and cytarabine in the loaded nanoparticles while the scanning electron micrograph (SEM) image depicts smooth surface, spherical shape and uneven size of nanoparticles (100-300 nm). The prepared nanoparticles were loaded with cytarabine, a well-known anticancer drug, and the release dynamics of entrapped drug was investigated as a function of various experimental factors, such as percent loading of the drug, chemical architecture of the nanocarriers, and pH, temperature, ionic strength, and nature of the release medium. The nanoparticles were also studied for their water sorption capacity by optical microscopic method taking advantage of the aggregation of nanoparticles. The drug release process was analyzed kinetically using Ficks power law, and a correlation was established between the quantity of released drug and swelling of the nanoparticles. (c) 2006 Wiley Periodicals, Inc.