The superfamily of collagens is comprised of 27 members (reviewed by Myllyharju & Kivirikko, 2004; Ricard-Blum & Ruggiero, 2005; Ricard-Blum et al., 2005), which are classified into several subgroups according to their structural features and supramolecular assemblies. Fibrillar collagens and FACITS (Fibril-Associated Collagens with Interrupted Triple helix) are described in the paper by Ruggiero et al. in this issue. Our paper reports recent advances on collagens associated to basement membranes. It focuses on the multiplexin family (including collagens XV and XVIII) and on membrane collagens present in skin, namely collagens XIII and XVII. The mechanisms leading to the shedding of their ectodomain from cell membrane and the biological roles of their shedded domains are discussed. The last part of the paper is devoted to several fragments of basement membrane collagens, called matricryptins or matrikins, and to their biological activities.