effect of hybridized liposome by novel modification with some polyethyleneglycollipids this study is about hybridized liposome contained doxorubicin hyldox that has dual properties of stability in blood and incorporation in tumor cells we used two kinds of polyethyleneglycollipids which are 1monomethoxypolyethyleneglycol23distearoylglycerol pegdsg with an alkyl anchor and cholesterolpeg pegcho with a cholesterol anchor hyldox was evaluated on antitumor activity in vivo dox uptake into tumor cells and dox cytotoxicity in vitro both tumor size and tumor weight in the hyldox group were decreased compared with those in the control group hyldox had increased dox uptake into p388 leukemia cells compared with the single pegdsg modified liposomes moreover the ic50 value used as the index of the effect of cytotoxicity significantly decreased in hyldox we suggested that these results of dox uptake and cytotoxicity contributed to pegcho on liposomal membrane the peg modified liposome with only pegcho cannot have a prolonged circulation time but the hyldox which was modified with mixing peglipids pegdsg and pegcho showed stability in blood and incorporation in tumor cells as the result of these experiments hyldox were observed to be useful in terms of cell transition at target site as shown by high dox uptake into cell and high cytotoxicity because pegcho has good incorporated into tumor cell hence it is expected that hyldox has novel functions