The group of secreted mucins has eight members: five genes encode the gelforming mucins (MUC2, MUC5AC, MUC5B, MUC6 and MUC19) and three genes encode the soluble mucins (MUC7, MUC8 and MUC9). Gel-forming mucins share structural and evolutionary features with von Willibrand Factor. Soluble mucins differ from gel-forming mucins in that the former all do not have the von Willibrand Factor specific domains while mucin specific tandem repeat-containing domain is a common feature of all secreted mucins. Genes encoding the soluble mucins are located at different chromosomes, whereas all gel-forming mucin genes except MUC19 are clustered on chromosome locus 11p15.5 and the MUC19 gene is located on chromosome 12. Structural aspects and functions of the secreted mucins are discussed.