N-Methylquipazine is a tertiary amine analog of quipazine. It binds at 5-HT3 sites with an affinity similar to that of quipazine. N-methylquipazine has a low affinity for 5-HT1A, 5-HT1B, 5-HT2, a1, a2 and muscarinic receptors. It produces a concentration-dependent increase in extracellular dopamine levels in the anterior medial prefrontal cortex. This action is dependent on the presence of Ca+2, is impulse-dependent, and depends on newly synthesized dopamine stores. The increase in the anterior medial prefrontal cortex dopamine levels by n-methylquipazine is probably, not mediated by its interaction with the 5-HT3 receptor. It might be an be an attractive candidate as a radioligand for the PET studies of 5-HT3 receptors in man.