Summary A specific receptor for human atrial natriuretic peptide (h-ANP) was identified in the human kidney using the radioligand binding assay. Samples were prepared from non-malignant renal tissues obtained at nephrectomy of patients with renal carcinoma. Binding studies using [ 125I]hANP were performed at 0°C for 20 minutes and terminated by a rapid filtration technique. Scatchard plot analysis revealed [ 125I]hANP bound to a single class of binding site (Kd=0.4±0.2 nM) with a density of 16±4 fmol/mg protein in the renal cortex (n=7). The binding was rapid and maximal binding was obtained within 20 minutes after the start of incubation. Radioligand displacement was observed in a dose dependent fashion when cold hANP was entered into the reaction mixture.. However, unrelated agents, such as angiotensin II or 1-epinephrine, did not affect the binding. This is the first time characterization of the hANP receptor in the human kidney has been conducted using a Scatchard plot analysis.