S of relaxin family peptides and their receptors have been extensively reviewed (Ivell and Anand-Ivell, 2009; Smith et al., 2011; Bathgate et al., 2013a). In particular, the role of relaxin in female and male reproductive physiology have been well studied (Sherwood, 1994, 2004; Bathgate et al., 2013a, 2006c). For this reason, only brief overviews will be given here. A. Relaxin and Relaxin Family P