During recent years the writer has had occasion to infest many rabbits with cercarial cysts of Fasciola hepatica. In all but three instances the infested rabbits have been killed within about ten weeks of the commencement of the experiment. These three rabbits remained infested over a long period and are the subjects of this note. They were kept under conditions which appeared to exclude all opportunity for further fluke infestation and no accidental infestation has been observed among the considerable number of similar rabbits used in other experiments during these years.