The possibility of an extraterrestrial origin of biomolecule building blocks has been a subject of intense discussions for many years. The detection of amino acids in meteorites opens the possibility of a delivery of biomolecules synthesized in the interstellar medium or star-forming regions to the primeval Earth. Whereas it can be doubted if more complex species like amino acids can survive the strong UV radiation in the early Solar System, this does not necessary hold for more primitive precursor molecules like nitriles. These compounds can also be synthesized very efficiently in methane-nitrogen dominated atmospheres like the one present on Titan and the early ages of Earth. This Contribution focuses on the formation and degradation processes of nitriles in interstellar clouds and planetary atmospheres and on their possible role in the generation of biomolecules.