In a 24-month oral carcinogenicity study, Swiss mice (body weight of males, 27–32 g; body weight of females, 21–27 g; approximately 5.5 weeks old) were administered prucalopride 10, 20 or 80 mg/kg per day (n=120 (60 males and 60 females) per dose group). In a 1-month, repeated-dose oral toxicity study, SPF Wistar rats (Hannover sub-strain; male and female; body weight range, 120–168 g; approximately 4 weeks old) were administered prucalopride 20, 40 or 80 mg/kg per day (n=20 [10 males and 10 females] per dose group). In a 24-month oral carcinogenicity study in SPF Wistar rats (Hannover sub-strain) of approximately 5 weeks of age, male rats (body weight, 87–131 g) were administered prucalopride 5, 20 or 80 mg/kg per day (n=60 per dose group) and female rats (body weight, 82–112 g) were administered prucalopride 5, 10 or 40 mg/kg per day (n=60 per dose group). All mice and rats were obtained from Charles River, Sulzfeld, Germany, or from Biological Research Laboratories, Füllinsdorf, Switzerland. In single-dose and repeated-dose toxicity studies of mice and rats, all animals were observed daily for signs of clinical or behavioural abnormalities, some of which were CNS related; these included ptosis, convulsions, tremors, salivation, sedation, ataxia and hypothermia.