The ultrastructure of the phycobiont, Coccomyxa, was compared in some asco- and basidiolichens. All phycobionts investigated contained a single cup-shaped chloroplast, multivesicular bodies and large storage bodies. In the chloroplast of the phycobionts in ascolichens, many plastoglobuli occurred regularly whereas, in those of the basidiolichens, no plastoglobuli were present. The multivesicular bodies were associated with varying numbers of vesicles and storage bodies. The storage bodies increased when the lichens were kept dry for several months. By cytochemical tests, the lipid nature of these bodies was suggested. The possible function of the different structures is discussed in comparison with the ultrastructure of other lichens.