Ionically complexed nanoparticles were prepared from an anionic polysaccharide drug, heparin, entrapped by a positively charged chitosan polysaccharide. In this study, the encapsulation of heparin was studied to optimize the properties needed for its oral drug delivery. Chitosan, used in various biomedical applications, was selected as a cationic polymer for heparin encapsulation. These particles were prepared with a slightly positive charge and an appropriate size for oral drug delivery. In addition, the release profiles of these ionically complexed nanoparticles were improved by using FDA-approved stabilizers, such as pluronic non-ionic surfactant and polyvinyl alcohol. These results obtained in vitro suggest that these stabilized, ionically complexed nanoparticles may be well-suited for the oral drug delivery of heparin into the gastrointestinal tract.