Abstract: A time-release chemical delivery system in which a bioactive compound is attached to a polymeric biodegradable carrier by a hydrolyzable bond is disclosed. The bioactive compound can either be bound directly to the polymer or be attached to the polymer via a spacer group. The composition of the system is particularly effective for delivering medication systemically to a host animal over a prolonged period of time after being surgically implanted or injected subcutaneously. Biodegradable condensation polymers having reactive pendant groups, for example, poly-L-(glutamic acid), or derivatized poly-L-(glutamic acid) are effective as polymeric carriers.