The technique to detect all possible variants of mutations in 12, 13 and 15 codons of gene KRAS was developed on the basis of the pyrosequencing technology. The analytical characteristics of the developed technique were identified. The limit of detection for mutations G34T, G35A and G38A detected on the cloned control samples consisted 3%. The limit of blank for various mutations consisted from 0.3% to 4.1%. The system was tested on clinical samples. The 7 different types of mutations were identified and detected in quantitative format. No discrepancy of pyrosequencing data with results of sequencing according Sanger was established.