Self-incompatibility is one of the most crucial mechanism to prevent inbreeding in angiosperms. It is genetically controlled with one multiallelic S-locus whose expression depends on pistil or pollen tissue. The most spread auto-sterility systems in angiosperms consists of two types of SI: gametophytically (GSI) or sporophytically (SSI) controlled self-incompatibility. The rest of SI noticed in angiosperms are cryptic (CSI) and late ovarian (OSI). Three molecular mechanisms have been closely observed: S-RNase system (present in Solanaceae), calcium cascade system (present in Papaveraceae) and homomorphic SI type in Brassicaceae family. After 60 years of intensive scientific research, our knowledge of molecular mechanisms of self-incompatibility is still incomplete. Even the most researched S-RNase mechanism remains questionable. From all of the information presented in this review, it can be concluded that the two proposed models are most likely related. Ubiquitination targets ribonucleases while most of them which enter the cell through endocytosis are sealed off from the cytoplasm in the vacuole. The most important suggestion for future research is to set the point of interest in connecting these two models and test this hypothesis, as well as look into the exact location of cytotoxic activities of S-RNases. Papaveraceae type is one of the most researched mechanisms and most of its interactions are well-known. The newly discovered phenomenon where scientists managed to induct SI in a completely unrelated plant species opens up new possibilities for agronomical application and genetic research. The focus of this paper is to deliver current information on the topic of self-incompatibility, even though most of SI mechanisms are still poorly documented in the majority of plant families. Deeper study of this problem would offer valuable information for phylogeny and better explanation of evolutionary processes of angiosperms.