Generally, the number of genera and species of microflora were found to have decreased in the River Nile water treated with different doses (0.1-10 g dm-3) of four detergents (Biocleana, Lang, Omo and Tide). Algae are more sensitive to detergents than bacteria and fungi but some species were increased either slightly or markedly. No stimulatory effect was observed on bacteria by any of the detergents. The effect of detergents on fungi was different. The most tolerant fungal species was Penicillium chrysogenum Thom and may be regarded as a detergent- (pollution-) tolerant fungus.