The discovery of (pro)renin receptor, (P)RR, has made the renin-angiotensin system (RAS) more multifaceted. Interaction of renin and prorenin with this receptor has set a new perspective about the physiological functions, activation mechanism and pathophysiological roles of renin/prorenin. Uses of peptides mimicking the structure of the ligands have been very effective for determining structure-function relationship between the ligands and receptor. The probable pivotal role of decoy peptide region (R(10P)IFLKRMPSI(19P)) of prorenin prosegment was suggested for higher binding affinity of prorenin to (P)RR than that of mature renin. Recently, 'hinge' region peptide (S(149)QGVLKEDVF(158)) in renin/prorenin molecule has been reported. Bothrenin and prorenin can interact with (P)RR through the 'hinge' region. Furthermore, it has been proposed that prorenin has multiple binding sites whereas renin has a single binding site for (P)RR. To comprehend the activation mechanism of renin and prorenin after receptor binding, it is very important to understand their interaction with the receptor. Several kinds of peptides designed from the regions of the tertiary structure of renin and predicted model of prorenin facilitated the study of the in vitro binding mechanisms for renin and prorenin to (P)RR. Here, a series of recent in vitro studies was reviewed to discuss a possible binding mechanism of renin/prorenin to the (P)RR.