The treatment of 133 dogs with behavioural problems is reviewed. The problems most frequently presented concerned aggressive behaviour and/or fear (agonistic behaviour). The combination of problems of dominance and problem behaviour stimulating conditioning (PBSC) was a diagnosis made significantly more often than others. The owner's inability to control the dog appeared to be associated primarily with aggression, but also with fear, in the dog. In aggression as well as in fear, reinstatement of the appropriate ranking order was the usual goal of therapy. In cases of aggression the results of treatment were considered good or fair in 42 percent of the cases, moderate in 11, and bad in 41 percent of the cases. In those involving fear, the results were good or fair in 52 percent of the cases, moderate in 15, and bad in 25 percent. Hence treatment was only moderately successful. This reflects the need for more reliable and valid knowledge about symptoms, diagnostic methods and therapeutic possibilities.