1. Previous studies have shown that the blockade of the neuropeptide Y (NPY) Y1 receptors with N2-(diphenylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine amide (BIBP3226) induces anxiogenic-like reaction in rats tested in elevated plus-maze test. 2. The present study examined whether such a treatment is aversive using place conditioning in a two-compartment apparatus. Locomotor activity was measured in open field test. 3. Pairings with potentially anxiogenic dose of BIBP3226 (5 micrograms/6.5 microliters, i.c.v.) produced a conditioned aversion for the drug-associated place, whereas the locomotor activity in the open field test was not affected by this dose of BIBP3226. 4. These data suggest that the blockade of central NPY Y1 receptors is aversive and provide additional evidence to the hypothesis that the NPY Y1 receptors are involved in the regulation of affective states.