For more than a year, the algal vegetation of a particular part of the saltmarsh “De Mok” was studied, by means of permanent quadrats. Three communities of surface algae were distinguished: the Vaucheria subsimplex/ Enteromorpha prolifera/ Microcoleus community, the Vaucheria coronata/ Enteromorpha prolifera/ Microcoleus community and the Vaucheria coronata/ Rhizoclonium /Microcoleus community. Each of these occupied a consecutive zone, from low to high, in the marsh and had a number of characteristic species, for some of which a significant correlation to higher or lower situated permanent quadrats could be shown. A Blidingia minima community, epiphytic on Salicornia stems, with the red alga Bangia atropurpurea as a characteristic species, was intermingled with the Enteromorpha prolifera unit of the first community during a part of the year.