The microbiological assessment of fourteen sampling sites distributed in Abu Dhabi Coast, were surveyed monthly during October 1989 until September 1990 except for February and April 1990. The saprophytic bacteria, salt tolerant saprophytic bacteria, gram-negative bacteria total and faecal coliforms were determined. In general, the numbers of all determined bacterial groups were found to be correlated with each other and in most cases they fluctuate together. Furthermore, the bacterial flora of the coastal water is markedly affected by water temperature, sampling sites and sampling time. The bacterial content of most site fluctuated maximally during August and September (late summer). The natural self-purification process of coastal water samples was clearly observed. The predominant saprophytic bacterial genera and the common coliform species occurred in the study areas were identified.