SUMMARY: An implementation of BLAST for searching the PRINTS database is presented. The interface allows submission of either protein or DNA queries, and returns the familiar form of output, but modified by means of direct links both to the familial discriminators in PRINTS and to fingerprint profile visualization software. The server thus couples the rapidity of BLAST searching with the sensitivity of fingerprint diagnoses, providing alternative perspectives on a given query. AVAILABILITY: http://www.biochem.ucl. ac.uk/cgi-bin/wright/printsBLAST.cgi