Prebiotic chemistry plays a central role in the investigation of the possible scenarios of the early chemical environments. Its goal is to shed light on the events involved in the synthesis of initial biomolecules and on the selforganization processes that led the last common ancestor. Even though a well defined scenario for the physicochemical conditions on the primitive Earth is not available, one can assume that a synthetic pathway, in order to be considered prebiotic, should use the simplest chemicals and the most common conditions present at that time. Low molecular weight molecules such as hydrogen cyanide and formaldehyde, easily formed from the primitive atmosphere by ultraviolet light, heat or electric discharge as energy sources, have been considered as prebiotic precursors. Here we focus on the attempts to identify the prebiotic events originating purine and pirimidine nucleic acids bases, the necessary components for the assembling of nucleosides, nucleotides and oligonucleotides.