Twenty out of 200 isolates of cyanobacteria mainly from saline soils of Songnen Plain of China were successfully grown on BG11 N-free medium.The nitrogen-fixing activity was then demonstrated for the 20 isolates in modified BG11 medium using the acetylene reduction assay.All of them possessed appreciable nitrogenase activity(acetylene reduction)under non-saline conditions;however,at 5%NaCl only 60%of the isolates exhibited a high rate of this activity and 25%were completely negative under these conditions.The cyanobacteria isolates grew well in BG11 medium;nevertheless,growth of the majority of isolates was reduced by about 25-85% in the same medium containing 5%NaCl.Cellulolytic activity was detected in 50%of the 20 strains,amylolytic in 45%,and pectinolytic in 10%of the isolates.The cyanobacteria isolates showed also enzymatic activity under saline conditions(6%).The preliminary identi-fication indicated that seven isolates were Nostoc,two were Microcystis,four were Oscillatoria,six were Anabaena,and one isolate was Synechococcus. Twenty out of 200 isolates of cyanobacteria mainly from saline soils of Songnen Plain of China were successfully grown on BG11 N-free medium. The nitrogen-fixing activity was then demonstrated for the 20 isolates in modified BG11 medium using the acetylene reduction assay. All of However, at 5% NaCl only 60% of the isolates exhibited a high rate of this activity and 25% were completely negative under these conditions. The cyanobacteria isolates grew well in BG11 medium; nevertheless, growth of the majority of isolates was reduced by about 25-85% in the same medium containing 5% NaCl. Cellulolytic activity was detected in 50% of the 20% of amylolytic in 45%, and pectinolytic in 10% of the isolates. The cyanobacteria isolates also enzymatic activity under saline conditions (6%). The preliminary identi-fication indicated that seven isolates were Nostoc, two were Microcystis, four were Oscillatoria, six were Anabaena, and one isolate was Synechococcus.