An interstrain comparison was conducted between male spontaneously hypertensive rats and Wistar-Kyoto rats, in both the open field and the elevated plus-maze. Wistar-Kyoto rats, as compared to the hypertensive animals, showed, beside an attenuated locomotor activity in both test situations, a higher reaction to aversive environments (less entries into the central area of the open field and less visits to the open arms of the elevated plus-maze). Chlordiazepoxide, as potent anxiolytic, increased (1) general activity, (2) the frequency of entries into the open area of the open field, and (3) the number of visits to the open arms of the elevated plus-maze in both rat strains.