Twenty species of Fungi imperfecti, including strains from freshwater, estuarine and marine habitats in the environs of the middle and lower Neretve River, Yugoslavia, were collected, purified and identified. Strains of nine species from fresh, brackish, and sea water were grown on various NaCl concentrations. These fungi exhibited a wide amplitude of salt tolerance. In general, the strains from fresh water grew best at or were able to tolerate the lower NaCl concentrations. The sea-water strains grew best at and could tolerate the higher NaCl concentrations. Brackish-water strains were found to be more like strains isolated from fresh water than from sea water. Brackish-water strains were able to grow well in zero or low concentrations of NaCl, but they could not do as well at the higher NaCl concentrations. The results of the laboratory experiments with NaCl concentrations support the findings in nature. All twenty species of these fungi were tested for their ability to decompose lignin, utilize phosphate and degrade lecithin. Five species gave a positive reaction on gallic acid medium; five species were able to utilize lecithin; and seven species were active in utilizing tribasic calcium phosphate. © 1969 Dr. W. Junk N. V.