The laminins are a family of extracellular matrix glycoproteins localized in the basement membrane that separates epithelial cells from the underlying stroma. They are also found in basement membrane surrounding fat, muscle and peripheral nerve cells. The laminins are large trimeric glycoproteins comprising three disulphide-bonded chains. They are the first extracellular matrix molecules to be observed in the developing embryo and have potent biological activities. In addition, there have been new developments in the number and localization of the homologues of the laminin chains and the role of laminin in neuromuscular disease. Their primary role is in cell-matrix attachment, but many additional biological activities, including promoting cell growth and migration, tumour growth and metastases, neurite outgrowth, nerve regeneration, wound repair and graft survival, have been demonstrated. Many of these biological activities are duplicated by proteolytic fragments of laminin and by small laminin-derived synthetic peptides. These laminin-derived peptides may be useful clinical reagents for accelerating wound healing with minimal scarring or for blocking tumour metastases.