The mucus from 2-day-old and 3-week-old pigs was separated into polymeric mucus glycoprotein, degraded mucus glycoprotein subunit, and low-molecular-weight glycoprotein. 2. The low-molecular-weight glycoprotein fraction contained significant amount of mannose. 3. The degraded mucus glycoprotein subunit and the low-molecular-weight glycoprotein decreased in the mucus from older pigs.