AbstractDopamine receptors are the principal targets of drugs used for the treatment of neuropsychiatric disorders such as schizophrenia and Parkinson's disease. This unit details protocols for radioligand binding assays for various subtypes of dopamine receptor. The scope is limited primarily to the most widely used, well established protocols for binding assays, which employ commercially available tritiated ligands. Protocols are given for radioligand binding assays for D1‐like and D2‐like receptors. A protocol for the putatively selective labeling of D3 sites is also presented. The basic protocols are used to assay dopamine receptors in membrane homogenates, and support protocols describe the preparation of these homogenates from organs and from cultured cells. The calculation of the radioligand's molar concentration is also included.