The invention provides novel formulations of guanylate cyclase-C (“GCC”) agonist peptides and methods for their use in the treatment of gastrointestinal diseases and disorders, including gastrointestinal cancer. The GCC agonist formulations of the invention can be administered either alone or in combination with one or more additional therapeutic agents, preferably an inhibitor of cGMP-dependent phosphodiesterase or a laxative.
