FIELD: molecular biology, microbiology, medicine. SUBSTANCE: method involves amplification of gene rpoB fragment to obtain a single-stranded fluorescently labeled product by method of polymerase chain reaction. Biochip for assay of rifampicin- -resistant mycobacterium is prepared and hybridization of amplified labeled product on biochip is performed. Results of hybridization are recorded and explained their by comparison of fluorescence signals obtained in completed and uncompleted hybridization. Biochip is micromatrix with cells where oligonucleotide set is immobilized and their sequences are given in description of the invention. Upper row of biochip has oligonucleotides that are complementary to DNA sequence of wild type. Corresponding column under each cell has oligonucleotides that are complementary to DNA sequences of mutant type responsible for exchange of a single amino acid. Diagnosis of resistance of mycobacterium to rifampicin is carried out by determination of single nucleotide exchanges in pathogen DNA. Invention ensures to perform analysis from clinical sample directly, to assay some mutations simultaneously. EFFECT: improved method of assay, decreased cost and time of analysis. 11 cl, 6 dwg, 2 tbl, 3 ex
