Data are described on identification, isolation and purification of restricting endonuclease Sau 6782 as well as on estimation of the enzyme recognition site. Conditions were developed for growing of Staphylococcus aureus 6782 strain, which enabled to produce a maximal yield of the restricting activity containing minimal level of nucleases. The procedure for isolation and purification of restrictase Sau 6782 involved affinity chromatography on Blue Sepharose and cation exchange chromatography on phosphocellulose PII. The enzyme preparation obtained was free from impurities of unspecific nucleases. The yield of the Sau 6782 restrictase constituted 1,000 un from 1 g of the culture cells. Restrictase Sau 6782 recognized the nucleotide sequence 5'...GATC...3' and was the isoshizomere of the Sau 3A enzyme.