A novel photopolymerized hydrogel material has been developed for use as a drug delivery vehicle for bioactive materials. The hydrogel precursor consists of polyethylene glycol copolymerized with an α-hydroxy acid and with acrylate termini at each end. The precursor is water-soluble and non-toxic. The precursor polymerization conditions are very mild, and polymerization can be carried out in direct contact with cells and tissues. The degradation rate and permeability of the hydrogel can be altered by changing the composition of the precursors, allowing use of this class of materials for a variety of applications. In vitro release of proteins and oligonucleotides is reported. © 1995.