Medical genetics made during the last decades immense advances and new findings from the sphere of fundamental research are increasingly penetrating into different clinical disciplines. The greatest attention was concentrated on investigations devoted to the molecular etiology of malignant diseases and the molecular mechanism of embryonic development. Mapping of the human genome is the prerequisite for identification of serious diseases at the gene level. Control of these problems opens possibilities of aimed diagnostics at the molecular level during the postnatal period and as well as the prenatal one. So far we possess knowledge required for genetic counselling and possible prevention. With the extension of our knowledge on gene mechanisms we find that originally apparently clear mechanisms of heredity are much more complicated. In the last three years also the possibility arose of gene therapy of some malignomas and other pathological conditions of the organism. Hitherto assembled experience is relatively optimistic although a major development of these techniques is foreseen only at the end of this millenium. Medical genetics advanced greatly in the prenatal diagnosis of inborn developmental and hereditary foetal diseases. Gradually different screening programmes were introduced to evaluate the status of the foetus in utero. At present also predictive tests are available for some serious diseases. All these methods and technologies are associated with many ethical, moral and psychosocial problems which must be gradually resolved.