5-OH-DPAT is a synthetic compound that acts as a dopamine receptor agonist with selectivity for the D<sub>2</sub> receptor and D<sub>3</sub> receptor subtypes. Only the (S)-enantiomer is active as an agonist, with the (R)-enantiomer being a weak antagonist at D<sub>2</sub> receptors. Radiolabelled <sup>11</sup>C-5-OH-DPAT is used as an agonist radioligand for mapping the distribution and function of D<sub>2</sub> and D<sub>3</sub> receptors in the brain, and the drug is also being studied in the treatment of Parkinson's disease.