Comparison of the serotonin 5-HT2A receptor affinities of chain lengthened and N-alkylated analogues of the novel ligand 9-aminomethyl-9,10-dihydroanthracene (AMDA) and a structurally similar prototypical tricyclic amine imipramine suggests that the two agents bind to the receptor in different fashions. The demonstration that AMDA is highly selective for serotonin receptors (5-HT2A, K = 20nM; 5-HT2C, Ki=43nM) versus the dopamine D2 receptor (Ki>10,000nM), as well as the serotonin and norepinephrine transporters (Ki>10,000nM) further suggests that AMDA and the nonselective ligand imipramine interact with these target macromolecules in different ways.