A galactan was isolated in 98% purity from the pectic substance isolated from the unripe fruit of papaya (Carica papaya). Hydrolysis of the fully methylated galactan gave 2,3,4-tri-, 2,3,6-tri-, and 2,3,4,6- tetra-O-methyl-D-galaotose in a mole ratio of 18 : 38 : 1. The structure of galactan is discussed in the light of the results of methylation and periodate oxidation studies.