A redescription of Blennius cristatus L. is made on the basis of 21 specimens collected in the same locality as the Linnaeus' type specimen of the group, in the Distrito Federal, Brazil, and belonging to the collections of the Museu Nacional, Rio de Janeiro. This is the author's first paper of a projected series on the Brazilian representatives of the family Blennidae. The present description is based especially on the skeleton, and is accompanied by a bibliographic analysis and considerations on the synonymy of B.cristatus. New morphological details are presented, bringing a better understanding of the species, and clearing up some nomenclatura! confusions due to insufficient descriptions in previous works on the same group. A table of measurements and 11 text figures complete the paper.