The present invention relates to a process for labeling a synthetic or natural ribonucleic acid (RNA). It also relates to RNA fragments, which have been labeled by fragmenting the RNA to free a terminal phosphate of each fragment for further reaction, and labeling each fragment at the freed terminal phosphate which is located at the 3′ end and/or the 5′ end of each fragment of the RNA, and to the use of such RNA fragments, for example, in the field of medical diagnosis.