Combination chemotherapy has been a primary management for cancer. Thus a drug delivery system which can administer several drugs simultaneously and control the drug release at the cancer site is desired. Here we synthesized hyperbranched poly(amine-ester) (HPAE) macromers with different degrees of terminal C=C modification to make injectable hydrogels as a multi-drug delivery system. The aqueous solutions of the macromers were fast transformed into hydrogel at body temperature with a low concentration (0.05 wt%) of ammonium persulfate (APS) but no activator for accelerating the polymerization, since the HPAE macromer with tertiary amines and APS themselves formed a redox system as initiator. Three different types of drugs, doxorubicin hydrochloride (Dox), 5-fluorouracil (5FU) and leucovorin calcium (LC), were used as model drugs in this experiment. This system allows locally releasing single and/or combinations of anticancer drugs simultaneously by a controllable way. Behaviors of drug release can be controlled by the drug-loading methods or/and the C=C modification degree of macromers loaded with the drug molecules. The drug release period could be prolonged when the drug was loaded into the macromers with high content of C=C. The HPAE macromers exhibited good biocompatibility which was evaluated in L929 and MCF7 cell lines using MTT cell proliferation assay. The swelling behavior and degradation of HPAE hydrogels in vitro were also examined. These results suggest that the HPAE hydrogels hold great potential for use as injectable systems for locally delivering single and/or multiple drugs in chemotherapy of cancer. (C) 2010 Elsevier Ltd. All rights reserved.