TODAY THE Nobel Foundation announced that the Nobel Prize in Physiology and Medicine goes to Andrew Fire and Craig Mello for their groundbreaking work in RNA silencing, also called RNA interference (RNAi). These researchers discovered that introducing short double-stranded RNA fragments into a cell activates a cellular mechanism that silences expression of a gene with a complimentary RNA transcript by destroying these transcripts. While recently some adverse effects of this technology in gene silencing in living animals were discovered, it remains promising for therapy for various illnesses. RNAi may in future be useful against cancers which overexpress certain genes, or against genetic disorders in which the body makes a mutant protein. Even if RNAi is never therapeutically useful, it will remain a valuable technique in genetic research. This Nobel Prize was awarded unusually soon after the initial publication of this research, and is well deserved.