Intracellular concentration of cGMP depends on the activity of guanylate cyclase, responsible for its synthesis, on the activity of cyclic nucleotide degrading enzymes - phosphodiesterases (PDEs). There are two forms of guanylate cyclase: the membrane-bound cyclase and the soluble form. The physiological activators of the membrane guanylate cyclase are natriuretic peptides (NPs), and of the cytosolic guanylate cyclase - nitric oxide (NO) and carbon monoxide (CO). Intracellular cGMP signaling pathways arise from its direct effect on the activity of G protein kinases, phosphodiesterases and cyclic nucleotide dependent cation channels. It has been shown in recent years that cGMP can also affect other signal pathways in cell signaling activity involving Wnt proteins and sex hormones. The increased interest in the research on the role of cGMP, resulted also in the discovery of its role in the regulation of phototransduction in the eye, neurotransmission, calcium homeostasis, platelet aggregation, heartbeat, bone remodeling, lipid metabolism and the activity of the cation channels. Better understanding of the mechanisms of action of cGMP in the regulation of cell function can create new opportunities for the cGMP affecting drugs use in the pharmacotherapy.