The chitosan-coated magnetic nanoparticles (CS MNPs) were prepared as carriers of 5-Fluorouracil (CS-5-Fu MNPs) through a reverse microemulsion method. The characteristics of CS-5-Fu MNPs were determined by using transmission electron microscopy (TEM), FTIR spectroscopy and vibrating-sampling magnetometry (VSM). It was found that the synthesized CS-5-Fu MNPs were spherical in shape with an average size of 100+/-20 nm, low aggregation and good magnetic responsivity. Meanwhile, the drug content and encapsulation rate of the nanoparticles was 16-23% and 60-92%, respectively. These CS-5-Fu MNPs also demonstrated sustained release of 5-Fu at 37 degrees C in different buffer solutions. The cytotoxicity of CS-5-Fu MNPs towards K562 cancer cells was investigated. The result showed that CS-5-Fu MNPs retained significant antitumor activities. Additionally, it was observed that the FITC-labeled CS-5-Fu MNPs could effectively enter into the SPCA-1 cancer cells and induced cell apoptosis.