Variant subclasses of cell lines derived from small cell lung cancers have previously been characterized, having distinctive biochemical, morphological and growth properties compared to the classic lines. Both types of small cell lung cancer express features suggesting that they are derived from neuroectodermal cells. We compared the capacity of these two types of lung cancer cell lines to synthesize the extracellular matrix glycoproteins, fibronectin and laminin, and also analysed a few other non-small cell lung cancer lines, as controls. We found that the cell lines of the pure type did not produce laminin or fibronectin, whereas the cell lines of the variant type synthesized laminin, and the non-small cell lung cancer lines produced either laminin or fibronectin. These findings suggest that the variant form of small cell lung cancer may be derived from a primitive neuroectodermal cell, with both neural and epithelial features, whereas the classic type is derived from a more mature cell with predominantly neuronal features. The differences in extracellular matrix synthesis, and laminin in particular, may explain some of the in vitro and in vivo characteristics of the tumour.