A programme of pre-clinical safety evaluation of ondansetron has been undertaken which involved a series of studies - single dose studies, repeat dose studies, reproduction studies, genotoxicity studies, oncogenicity studies, local irritancy studies, and a hypersensitivity study. Ondansetron was found to have a very good safety profile, and the only toxicity identified was associated with central nervous system activity when near lethal doses were administered. It was not genotoxic and had no reproductive or oncogenic potential.