Compounds selected from: ##STR00001## where DRUG-OH, DRUG-COOH and DRUG-NH.sub.2 are biologically active compounds; each X is independently selected from --CH.sub.2COO-(glycolic acid moiety), --CH(CH.sub.3)COO-(lactic acid moiety), --CH.sub.2CH.sub.2OCH.sub.2COO-(dioxanone moiety), --CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2COO-(caprolactone moiety), --(CH.sub.2).sub.yCOO--, where y is 2-4 or 6-24 and --(CH.sub.2CH.sub.2O).sub.zCH.sub.2COO--, where z is 2-24; each Y is independently selected from --COCH.sub.2O-(glycolic ester moiety), --COCH(CH.sub.3)O-(lactic ester moiety), --COCH.sub.2OCH.sub.2CH.sub.2O-(dioxanone ester moiety), --COCH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2O-(caprolactone ester moiety), --CO(CH.sub.2).sub.mO--, where m is 2-4 or 6-24 and --COCH.sub.2O(CH.sub.2CH.sub.2O).sub.n-where n is between 2-24; R' is hydrogen, benzyl or an alkyl group, the alkyl group being either straight-chained or branched; and p is 1-6. Multi-functional compounds and drug dimers, oligomers and polymers are also disclosed.