The effects of natriuretic peptides on cGMP formation and [125I]ANP binding in human trabecular meshwork cells were investigated. CNP at 1μM stimulated cGMP formation∼18–25 fold, with a half maximal effective concentration∼20–30nM. BNP at 1μM stimulated∼7 fold, while ANP stimulated cGMP formation 2-fold at 1μM but had little or no effect at concentrations below 1μM. Displacement binding of [125I]ANP to intact TM cells in the presence of unlabeled ANP indicated a single binding site with a dissociation constant∼0.15nM. c-ANP, which binds specifically to natriuretic peptide C receptors, displaced>95% [125I]ANP binding to surface receptor sites with a half-maximal effective concentration comparable to that of ANP or BNP. c-ANP had no inhibitory effect on CNP stimulation of cGMP formation. The data suggest that human TM cells possess natriuretic peptide B receptors as the primary guanylyl cyclase-containing subtype and C receptors as the numerically predominant subtype of natriuretic peptide receptors.