The effects of propofol alone or propofol and ketamine for the induction of anaesthesia in dogs were compared. Thirty healthy dogs were premedicated with acepromazine and pethidine, then randomly allocated to either treatment. Anaesthesia was induced with propofol (4 mg/kg bodyweight intravenously) (group 1), or propofol and ketamine (2 mg/kg bodyweight of each intravenously) (group 2). Anaesthesia was maintained with halothane, delivered in a mixture of oxygen and nitrous oxide (1:2) via a non-rebreathing Bain circuit. Various cardiorespiratory parameters were monitored at two, five, 10, 15, 20,25 and 30 minutes after induction, and the animals were observed during anaesthesia and recovery, and any adverse effects were recorded. During anaesthesia, the heart rate, but not the systolic arterial pressure, was consistently higher in group 2 (range 95 to 102 beats per minute) than in group 1 (range 73 to 90 beats per minute). Postindudion apnoea was more common in group 2 (11 of 15) than in group 1 (six of 15). Muscle twitching was observed in three dogs in each group. Recovery times were similar in both groups. Propofol followed by ketamine was comparable with propofol alone for the induction of anaesthesia in healthy dogs.