A series of substituted N-[(tetralin-1-yl)alkyl]piperidines and a number of related N-di-n-propyl-[(tetralin-1-yl)alkyl]amines were prepared. Structural modifications such as piperidine substitutions, intermediate chain lengthening, and the nature of the aromatic ring were explored in order to identify structural requirements for selective sigma 1 affinity. They were tested in radioligand binding assays on sigma 1, 5-HT1A and 5-HT2 serotonergic, PCP (phencyclidine), and D-2 dopaminergic receptors. Almost all the compounds reported here showed a high to superpotent sigma 1 affinity, and some compounds also demonstrated a widespread selectivity over the other receptors. In [3H]-(+)-pentazocine binding, 3,3-dimethyl-1-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)-n- propyl] piperidine (24) and 3,3-dimethyl-1-[4-(1,2,3,4-tetrahydronaphthalen-1-yl)-n- butyl]piperidine (26) reached the lowest Ki values (0.4 and 0.8 nM, respectively); compound 24 also demonstrated a considerable PCP affinity (Ki = 34.2 nM), whereas compound 26 was suitably selective. Furthermore the presence of a 4-benzyl substituent on the piperidine ring (compound 16, Ki = 3.9 nM on sigma 1 sites) caused an increase in 5-HT1A affinity (Ki < 0.14 nM).