Phenotype and molecular approaches were applied to the study diversity of 14 original soil Nostoc strains. Obtained data were compared with other molecular and phenotypic data of soil and symbiotic strains. Morphology of cells, filaments, hormogonia and mucilaginous sheaths were observed. Special attention was paid to life cycles. Considerable variability was found by both (the molecular and the morphological) approaches. Nine clusters sharing similarity of 95% were obtained analysing 87 16S rDNA Nostoc sequences. In some of them a significant correlation between results of molecular and morphological approach was found. Published in Algological Studies, volume 117, issue 1, on pages 251 - 264, in 2005.