Behavioural problems directly affect the welfare of dogs and cats. The existence of a behavioural problem is a factor in the euthanasia and relinquishment of animals to shelters — a significant proportion of companion animals that are abandoned and euthanased are attributed to behavioural problems. Some behavioural problems are linked to stress and anxiety. In order to prevent and treat behavioural problems it is essential to have good epidemiological data. Most studies regarding the prevalence of behavioural problems use data from veterinary behaviourists. To our knowledge, no studies regarding the prevalence of small animal behavioural problems have been conducted in Spain. Therefore, a study was designed to estimate different aspects of canine and feline behavioural problems in Spain from the perspective of the veterinary practitioner. Of 433 valid questionnaires returned during a six month period, 46.2% of veterinarians referred cases to veterinary behaviourists and 12.3% to dog trainers; 34.7% never referred cases. Destructiveness, aggression and house soiling were the most frequent complaints regarding behavioural problems in dogs, whereas house soiling was clearly considered the main behavioural complaint in cats, followed by furniture scratching and excessive vocalisation. Behavioural modification was considered the most effective treatment for dogs, followed by drugs and castration. In cats the most effective treatment was castration, followed by drug therapy and behavioural modification.