Attention is now being paid for the protection of individuals and whole community against mutagenes such as x-rays and other ionizing radiations and also chemical mutagenes. Patients undergoing x-ray examination should be protected against unnecessary exposure of gonads to radiation. X-ray examination of the pregnant utrus to determine the presence of twins or the lie of the foetus is to be strongly deprecated. Rh haemolytic disease of the new born which is a genetically determined immunological disorders is now preventable by immunization of anti D globulin.