The invention relates to a method for producing a ribonucleic acid (RNA) molecule composition comprising n different RNA molecule species, the method comprising a step of RNA in vitro transcription of a mixture of m different deoxyribonucleic acid (DNA) molecule species in a single reaction vessel in parallel, i.e. simultaneously, and a step of obtaining the RNA molecule composition. Also provided is the RNA composition provided by the inventive method and a pharmaceutical composition comprising the same as well as a pharmaceutical container. Moreover, the invention provides the RNA composition and the pharmaceutical composition for use as medicament.
