The present work was aimed to study local variations of epiphytic microalgal distribution, biomass, and abundance at the northern part of Delta Egypt (Damietta, El- Deepa, Qualabshu, Kafr- Elshiekh and Rosetta) on the surface of a wide spread hydrophyte (Phragmites australis) during the year 2005. One hundred and forty one epiphytic algal species were recorded at the stations. The most dominant class of these species was Bacillariophyta; it represented 95.7 % of the total epiphytic species. Dinoflagellate was represented by 5 species, while each of Cyanophyta and Chlorophyta was represented by only one species. The distribution and abundance of these epiphytic microalgae were studied to be used as bioindicators of water quality assessment. To achieve this purpose, physicochemical analysis of water and biological analysis of epiphytic microalgae were evaluated. The results of diversity index revealed that water quality fluctuated from heavy to slight polluted water while the saprobity level point out to a univocal oligosaprobity and universal a- mesosaprobity.