Abstract: Poly(orthoester) co- and homopolymers and poly(orthocarbonate) co- and homopolymers comprising (1) a repeating dioxycarbon unit in the polymeric backbone having a plurality of organic groups pendant therefrom, and (2) a bridging moiety having at least one carbonyloxy group contained therein are disclosed. The polymers are represented by the formula: ##STR1## WHEREIN R is a bridging moiety and is either R.sub.1 or R.sub.2 arranged in a random manner along the polymeric backbone to form a copolymer containing both R.sub.1 and R.sub.2 with R.sub.1 an aliphatic, an alicyclic or an aromatic group and R.sub.2 is a ##STR2## GROUP WITH R.sub.1 as defined and R.sub.3 an aliphatic, an alicyclic or aromatic group, or wherein R is a bridging moiety and is only R.sub.2 to form a homopolymer with R.sub.1, R.sub.2, and R.sub.3 as defined above, and a is 0 to 1, b is 2 to 6, and n and the sum of x and y are positive integers.