text: MODOMICS is a comprehensive database that contains information about RNA modifications. MODOMICS provides the following information: the chemical structure of the modified RNAs, the RNA modifying pathways, the location of the modifications in the RNA sequences, the enzymes responsible for the modifications and liquid chromatography/mass spectrometry(LC/MS) data of the modified RNAs. As of November 2017, the database contained 163 different RNA modifications, as well as 340 different enzymes and cofactors involved in the modifications. This database classifies RNA modifying pathways according to their starting point. The LC/MS data has been very useful in determining the specific mass of the modified RNAs, which facilitates the identification of the modification.