Doxorubicin encapsulated solid lipid nanoparticles (DOX-SLNs) have already been invested for the chemotherapy of solid tumor, but after i.v. administration, DOX-SLNs are easily removed from circulation by the reticuloendothelial system (RES). In order to avoid clearance by RES, we prepared Poly (ethylene glycol) modified solid lipid nanoparticles (PEG-modified-SLNs) as carriers of doxorubicin, their correlative parameters and anti-tumor efficacy against hepatocarcinoma cells in vitro and in vivo were detected. The diameter of nanoparticles, determined by transmission electron microphotography, was 120±48 nm, and the loading efficiency was 68.6%. The release kinetics of DOX from PEG-modified-SLNs in vivo showed apparently controlled drug release efficiency. In vitro cytotoxicity assessed by MTT test was found to be concentration-dependent, and the effect of inhibition of hepatocarcinoma cell growth in vivo suggested that DOX-loaded-PEG-modified-SLNs could effectively inhibit the growth of hepatocarcinoma cells, which indicated favorable dosage-efficacy relationship. Therefore PEG-modified-SLNs might act as a promising carrier for controlled drug delivery. Keywords: Poly (ethylene glycol); solid lipid nanoparticle; stearic acid; Doxorubicin; chemotherapy; hepatocarcinoma