Seminal demonstration of the possibility of stable genetic modification of mammalian cells performed by Wacław and Elisabeth Szybalski opened the doors for gene therapy, the term coined by Wacław Szybalski already in 1962. In the next 60 years, numerous tools for gene delivery have been developed and applied for clinical research, culminating in the registration of several genetic therapies in Europe and the USA. Some of these strategies, aimed to treat severe combined immunodeficiencies, inherited forms of blindness, spinal muscular atrophy, some cancers, and genetic anemias, are the real hope for patients suffering from previously incurable diseases or the ones whose treatment was not effective. On the approaching 60th anniversary of gene therapy, combined with the 100th anniversary of the birth of Professor Wacław Szybalski (September 9th, 1921), who passed away on December 16, 2020, here I present the summary of the most important aspects of clinical applications of genetic therapies.