Abstract: A method and primary pair and kit for the in vitro amplification of nucleic acid using amplification primers in amplification reactions. There is used a pair of primers comprising oligonucleotide sequences complementary to a part of a Direct Repeat sequence of a microorganism belonging to the M tuberculosis complex of microorganisms, whereby hybridization to a Direct Repeat occurs and subsequently elongation of the hybridized primer takes place. The primers are such that elongation in the amplification reaction occurs for one primer in a 5' direction and for the other primer in a 3' direction.