Turnover of mucins in supramucosal gels is essential for the removal of surface contaminants, and the maintenance of normal mucosal barrier function. In addition to the well-known processes promoting the physical turnover of mucus gels, extracellular mucin degradation also requires the coordinated action of a range of enzyme activities including glycosidases and proteases. These are collectively termed "mucinase". Derangements of mucinase activity lead to downstream barrier defects and mucosal disease. This chapter is focussed on methods that can be used to assess the degradation of whole mucins and isolated mucin glycans. A range of approaches is described using labelled or unlabelled substrates utilised in assays based on 96-well plates, size exclusion chromatography, and NP-HPLC. These are suitable for defining the extent and progress of mucin degradation in different mucosal systems, and identifying abnormalities and critical control points.