Satisfactory results were obtained in the control of paratuberculosis in the province of Friesland during the period from 1954 to 1963. 465 Post-mortem findings positive for Johne's disease were observed on a number of farms prior to the start of control, in contrast with thirty-eight (8 per cent) positive findings in comparable conditions following this period. Unsatisfactory results in the Netherlands were reported in recent papers. This was attributed to modern stock farming in loose housings, the problems in carrying out free calf rearing and the fact that the johnin and complement fixation tests were not sufficiently reliable. It should also have been pointed out that incorrect regulations were adopted in controlling the disease, that the number of veterinarians engaged in studies under field conditions was not sufficient and, particularly, that investigators were not interested in working in the field. Vaccination may support control by reducing the pressure resulting from infection, though rapid elimination of shedders of M. Johnei as well as free calf rearing will continue to be essential in the effective control of 'clinical para-tuberculosis.