Relaxin induces sustained physiological responses, which brings into question the deactivation processes typical of most G protein-coupled receptors (GPCR) for its receptor, relaxin family peptide receptor 1 (RXFP1). Here, we examined relaxin-dependent phosphorylation of RXFP1 and the related insulin-like peptide 3 (INSL3) receptor, RXFP2, as well as the capacity of these receptors to recruit arrestins and internalize in response to ligand stimulation. We confirmed in HEK293T cells, expressing RXFP1 or RXFP2, that both receptors elicit prolonged cAMP responses up to 6 hours after stimulation. Receptors immunoprecipitated from ³²P metabolically labeled cells were used to investigate the agonist-specific phosphorylation. Rapid and robust receptor phosphorylation was not observed for either RXFP1 or RXFP2, although some ³²P-incorporation was observed at 30 min, however this was not statistically significant. In accord with this result, RXFP1 and RXFP2 demonstrated poor internalization in response to relaxin or INSL3, as compared to the angiotensin II type 1 receptor (AT₁R), which undergoes rapid and robust phosphorylation and internalization in response to angiotensin II. Additionally co-expression of GPCR kinases (GRKs) has no effect on the rate of internalization for either RXFP1 or RXFP2. Confocal microscopy was utilized to follow the trafficking of GFP-labeled arrestins after receptor activation. Neither RXFP1 nor RXFP2 activation results in recruitment of barrestins to the cell surface, whereas AT₁R rapidly recruits both arrestins-1 and -2. The apparent lack of classical regulation for RXFP1 and RXFP2 provides the molecular basis for the prolonged signaling and physiological actions of relaxin and related peptides.