This paper focuses on the diatom flora of Moss Creek in Antarctica that was collected during two summer (1995/96 and 2001/02) seasons. Of the 95 taxa identified in Moss Creek, two groups of diatom communities were distinguished. Achnanthes germainii, Eucocconeis ninckei, and Nitzschia homburgiensis, taxa indicative of unpolluted waters, dominated in the upper course of the creek. The other group was found in the lower reaches of the creek and included taxa indicative of eutrophic environments. In this part of the creek Mayamaea atomus associated with Nitzschia gracilis and Planothidium lanceolatum were dominant. In both sampling periods the species composition of the dominant taxa was similar with the distinct predomination of Mayamaea atomus. During the 1995/96 season, Nitzschia gracilis, N. homburgiensis, and Planothidium lanceolatum also occurred abundantly, whereas in 2001/02 the proportions of Nitzschia gracilis and Planothidium lanceolatum showed a slight increase.