Polyglycidol (PGly), a hyperbranched water-soluble polyether with numerous terminal hydroxyl groups, has structural similarities with polyethylene glycol. Our laboratory is exploring drug delivery using hyperbranched PGly-cytokines conjugates. Using human peripheral blood mononuclear cells and a tumor derived human B cell line, HBL-1; various PGly concentrations were tested for cytotoxicity. Our data indicated that hyperbranched PGly was similar in toxicity to PEG 8000, a commercial polymer. It was concluded that hyperbranched PGly did not exhibit significant cytotoxicity and showed promise for use as a biocompatible polymer. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2275-2278, 2009