[en] Radiation hygiene problems of industrial radioisotope applications are discussed. The observance of regulations is emphasised. Radiation protection is based on the principle of preventing early radiation damage and limiting late radiation damage to an acceptable level. The basic requirement is that the cumulated dose should be as low as possible, i.e., as low as is practically feasible in considering economic and social aspects. Notices 59/72 and 65/72, Collection of Laws, rule that if the limit of 3/10 of the maximum permissible dose is likely to be reached, control zones should be defined and marked at places of work where radioisotopes are handled. The characteristics of such a control zone are listed and the measures to be taken in case of accident are outlined. (B.S.)