Analogues of atriopeptin(103-125)amide were prepared having a disulfide bridge at positions different from that found in the natural product. Most of these conformationally perturbed peptides were found to bind selectively to one subclass of binding sites. Binding affinity to a class of specific binding sites that is not associated with any known biological activity (nonvasorelaxant or NVR binding sites) is unaffected or even modestly improved. Affinity for the receptor subclass that is associated with vasorelaxation (VR subclass) decreases in most examples. In several cases, binding to the VR subclass is below the limits of detection for the assay used here. The data demonstrate that binding of atrial peptides to VR receptors requires rigidly defined receptor/ligand interactions. In contrast, the NVR subclass of binding sites appears to tolerate changes in peptide structure quite well.