The role of lateral septal vasopressin (VP) in the modulation of spatial memory, social memory, and anxiety-related behavior was studied in adult, male Wistar rats. Animals were equipped with osmotic minipumps delivering the VP-antagonist d(CH2)5-D-Tyr(Et)VAVP (1 ng/0.5 microl per h) bilaterally into the lateral septum (LS). Subsequently, all rats were subjected to four behavioral tests. First, animals were tested in a spatial learning paradigm (Morris water maze; 12 trials), followed by the social recognition test. A possible role for VP in anxiety-related behavior was then studied in the shock-probe burying test and the elevated plus-maze, respectively. The results showed that VP receptor antagonism impaired social recognition and reduced open-arm activity in the plus-maze, while it had no effect on spatial learning (Morris maze) and shock-probe burying behavior. The results indicate a strong task-dependent specificity of lateral septal VP functioning.