A loss of the continuous linear deposit of basement membrane around invasive carcinomas has been suggested to correlate with their increased invasiveness. In contrast, extensive basement membrane deposition would represent a more favourable prognosis. The Engelbreth-Holm-Swarm (EHS) tumour, a transplantable neoplasm, is widely used for its ability to synthesize and deposit large amounts of basement membrane components. We have evaluated the metastatic potential of this neoplasm 2 months after subcutaneous inoculation. Histological examination of lung sections revealed the presence of numerous metastatic foci. The metastatic cells retained their organization into clusters surrounded by extracellular matrix. Both the 72 kDa and the 92 kDa type IV collagenases were detected by zymography in Triton or urea extract (matrigel) of primary tumour. These results cast doubt on the hypothesis that the extensiveness of basement membrane deposition might always be of prognostic value by being inversely correlated with the degree of invasiveness of a carcinoma.