The beneficial effects of vaccinations may be calculated by means of special formulas: (formulas: see text). In these formulas R means the risks of the disease with regard to special complications, r the comparable risk of vaccination, p the protection rate and t the duration of protection. A vaccination is beneficial, if N and Q greater than 1 and D greater than 0. Vaccinations which show low levels for N, Q and D must be reevaluated constantly by means of the above mentioned formulas. This control may be performed also by calculation of the border - risk Rlim = r/p.t and the epidemiologic trend. In case of whooping-cough according to the risk given by the WHO vaccination loses its beneficial effect at the end of 1976 and cannot be recommended therefore for general performance in middle Europe. On the other hand BCG-vaccination will have a beneficial effect for about another 30 years on a very low level. However, the beneficial effect is much more expressed, if the prevention of leucemic deaths, as quoted by Davignon and Rosenthal, is taken for granted.