Procollagen III N-terminal propeptide (PIIINP) is cleaved from procollagen III during collagen synthesis. Thus, circulating PIIINP increases during stimulation of collagen synthesis, and serum-PIIINP can be useful in the diagnosis and monitoring of a range of diseases characterised by increased collagen III deposition. PIIINP as a single marker is currently used in Denmark for monitoring disease activity in scleroderma and methotrexate-induced liver fibrosis. Besides, PIIINP forms part of the Elevated Liver Fibrosis (ELF) test, together with hyaluronic acid and tissue inhibitor of metalloproteinases (TIMP)-1, which has been demonstrated to be sensitive for alcoholic liver fibrosis.