Freeze fracture investigations have been carried out to investigate cellulose-synthesizing terminal complexes (TCs) in some chromophyte algae. The xanthophycean alga Botrydiopsis intercedens has TCs that consist of 3–8 diagonal rows of particles in the PF of the plasma membrane. A new type of TC was found in the phaeothamniophycean algae Phaeoschizochlamys mucosa, Phaeothamnion confervicola and Stichogloea doederleinii, where TC particles formed 2–3 linear rows. The TC of the eustigmatophycean alga Pseudocharaciopsis minuta was composed of a single linear row of particles and similar to that of phaeophycean algae so far examined. Each of the TCs found in the present study synthesized thin, ribbon-like cellulose microfibrils. A possible pathway of TC development in Botrydiopsis intercedens and TC evolution in the chromophytes are discussed.