We have previously shown that angiotensin II(3-7) [Ang II(3-7)] stimulates behavioural activity of rats similar to angiotensin II (Ang II). The involvement of AT1 angiotensin receptors in stimulating the behavioural activity of rats, using their selective ligand losartan (DUP 753), was examined. Ang II(3-7), given intracerebroventricularly (i.c.v.) at a dose of 1 nmol, significantly enhanced recall of a passive avoidance behaviour, object recognition, learning of conditioned avoidance responses (CARs) and apomorphine (1 mg kg-1, i.p.) stereotypy. Losartan (1 microgram, i.c.v.) did not alter any of the behaviours except for that measuring anxiety which was diminished both, in peptide treated and in control rats. On the other hand, losartan abolished Ang II(3-7) facilitation of recall of the passive avoidance, object recognition and the increase in apomorphine stereotypy. Losartan did not influence the increased rate of CARs acquisition after the peptide. None of the treatments significantly changed locomotor activity estimated in an open field. These data point to some involvement of AT1 angiotensin receptors in the behavioural activity of Ang II(3-7).