A database on UV-absorbing mycosporines and mycosporine-like amino acids (MAAs) has been constructed that provides information on various mycosporines and MAAs reported in fungi, cyanobacteria, macroalgae, phytoplankton and animals from aquatic and terrestrial habitats. It also contains information on biosynthetic routes of MAAs as well as on the absorption maxima and molecular structures of different mycosporines and MAAs ( Table 1S). This database provides necessary information for scientists working in the field of photoprotective compounds in fungi, cyanobacteria, macroalgae, phytoplankton and animals ( Table 2S). ( Tables 1S and 2S are available online as Supplementary material in the electronic copy of the journal as well as on our server <http://www.biologie.uni-erlangen.de/botanik1/html/eng/maa_database.htm>.)