We have modified our published method of RNA purification, developed to purify RNA from cartilage, tendon or synovium(4), to yield good quality RNA from sputum with relative simplicity and low cost. We have identified MMP-2, -9 and -14 in the sputum of healthy volunteers (unpublished pilot data) and will utilise this technique in the current study. Exhaled breath condensate (EBC) is completely non-invasive, requires no co-operation from individuals and provides information about a number of inflammatory and oxidation pathways. Markers of oxidative stress (8-isoprostane and hydrogen peroxide) and nitric oxide products can be measured in exhale breath condensate(5) and are related to disease activity in patients with COPD. Markers of oxidative stress increase in concentration in EBC during exacerbations of COPD are reduced after treatment with the antioxidant N-acetyl cysteine(6). Hydrogen peroxide is not stable and therefore 8-isoprostane is a preferable marker of oxidative stress unless the sample is measured on line.