The synthesis of 5-(cyclo)alkyl-5-phenyl- and 5-spiroimidazolidine-2,4-dione derivatives with an arylpiperazinylpropyl moiety (12-23) and their in vitro and in vivo pharmacological properties and molecular characteristics were described. The investigated compounds exhibited high affinity for 5-HT(1A) (13-22) and 5-HT(2A) (18, 20, 21, 23) receptors and diversified pharmacological profile. Compounds 17, 20 and 22 showed antagonistic, partial agonistic and agonistic activity, respectively, toward 5-HT(1A) receptor and they were investigated as potential antidepressants and/or anxiolytics. The most interesting compound 22 (1-[3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl]-3',4'-dihydro-2'H-spiro[imidazolidine-4,1'-naphthalene]-2,5-dione), a pre- and postsynaptic 5-HT(1A) receptor agonist produced an antidepressant-like effect, which was more pronounced than that of imipramine in the forced swim test in mice, without affecting locomotor activity. Moreover, compound 22 produced a weak anxiolytic-like effect in the four-plate test in mice. Molecular docking studies of compound 22 to the homology model of the 5-HT(1A) receptor showed that a 3',4'-dihydro-2'H-spiro[imidazolidine-4,1'-naphthalene]-2,5-dione moiety played an important role in stabilizing the ligand-receptor complex.