Mucins are extremely large and highly O-glycosylated glycoproteins synthesized and secreted by all wet-surfaced epithelia. Within the mucosal secretion they protect the underlying epithelium by forming a selective diffusion barrier against harmful substances and microorganisms, and act as lubricants to minimize shear stress. Variation in the character and quantity of secreted mucins is important to maintain the normal function of the epithelia (e.g., reproductive tract) but it may also reflect disease states. Understanding of the role of mucins has been limited by the lack of specific methods to detect and quantitate mucins in biological samples. Continuous progress in the development of specific antibodies against different mucin gene products has allowed the establishment of immunological techniques to perform these analyses. This chapter describes two protocols to quantify individual mucins from small-volume samples using indirect enzyme-linked immunosorbent assay (ELISA). These protocols allow a rapid, reproducible, and sensitive assay for these large molecules.