MLS1547 is a highly efficacious D2 dopamine receptor (D2R) G protein-biased agonist that does not recruit β-arrestin, and is an antagonist of dopamine-stimulated β-arrestin recruitment to the D2 receptor. MLS-1547 is the first D2 receptor agonist with close to full efficacy for G protein signaling (EC50 = 370 nM), but no ability to recruit β-arrestin.