Six strains of Klebsormidium flaccidum, one each of Klebsormidium subtilissimum, Ulothrix fimbriata, Stichococcus mirabilis, Stichococcus bacillaris, Pseudostichococcus monallantoides and Schizomeris leibleinii have been examined for the presence of urease or urea amidolyase (UAL-ase) and glycollate oxidase or glycollate dehydrogenase. All the Klebsormidium strains contained urease and glycollate oxidase; all the other algae examined contained UAL-ase and glycollate dehydrogenase. There was no evidence for the presence of both urease and UAL-ase activities in the same species. These results are consistent with the separation of the genus Klebsormidium from the Ulotrichales and its inclusion in the Charophyceae as defined by Stewart & Mattox (1975).