The anaerobic metabolism of Chlamydomonas moewusii under both light (160 lux) and dark conditions has been examined using manometric and enzymic techniques. During anaerobiosis starch is broken down to glycerol, acetate, ethanol, CO(2), and H(2). The release of CO(2) and H(2) comes to an end when the starch pool is depleted.There are only slight differences in the ratio of the end products of fermentation between light and dark metabolism. In the light, glycerol production is diminished and H(2) evolution is enhanced, whereas the production rate of all other end products generally does not change.