Techniques such as TALEN, CRISPR-CAS9 or prime editing (PE) can be used to edit the genome of various cells. Nevertheless, the genomes of hematopoietic stem cells and cells of the immune system may soon be edited more frequently for therapeutic purposes. This is due to the characteristics of blood and marrow as a tissue devoid of very complicated three-dimensional structures. In addition, induced pluripotent cells (iPSc), which are considered a source of cells with therapeutic potential, continue to pose a threat due to the developing teratomas. Moreover, knock out editing is easier than editing that changes the mutant gene to the correct one. Whereas cells such as CAR-T or virus-infected cells represent high-value targets for knockout genome editing systems in therapy. Immune system cells also seem to be particularly suitable as starting points for the creation of completely new cell types thanks to synthetic biology, in which genome editing techniques play an important role. All this makes CRISPR-CAS9 or PE more and more interesting for immunologists. The article discusses the basics of these techniques and explains the reasons for their imperfections.