A receptor for atrial natriuretic peptide (ANP) was purified 2700-fold, to apparent homogeneity, from cultured bovine aortic smooth muscle cells by affinity chromatography. The native ANP receptor has a molecular weight of 125,000 as determined by both metrizamide gradient centrifugation and nonreducing NaDodSO4/polysicrylamide gel electrophoresis. With 125I-labeled ANP as ligand, the purified receptor bound a maximum of 5.70 nmol of ligand per mg of protein and the dissociation constant was 4.0 x 10-1o M. Upon treatment with 10 mM dithiothreitol, the purified receptor migrated as a single band at Mr 60,500 in NaDodSO4/ polyacrylamide gel electrophoresis. These fmdings show that the holoreceptor for ANP in vascular tissue is composed of two subunits of identical apparent molecular weight, presumably linked by a disulfide bridge(s).