Oligonucleotide probes derived from Mycobacteria Kansasii capable of selectively hybridizing to Mycobacteria nucleic acid are disclosed. The oligonucleotide probe is selected from the group consisting of: (a) an oligonucleotide probe consisting essentially of the DNA sequence given herein as SEQ ID NO:1 (MK14); (b) oligonucleotide probes comprising fragments of MK14 which retain the capability of MK14 of selectively hybridizing to Mycobacteria nucleic acid; (c) oligonucleotide probes which hybridize to MK14 and are capable of selectively hybridizing to Mycobacteria nucleic acid; and (d) oligonucleotide probes which are complementary to any of the foregoing and are capable of selectively hybridizing to Mycobacteria nucleic acid. The probes are useful in nucleic acid amplification and hybridization assays for genus-specific detection of the mycobacteria, specific detection of M. kansasii and specific detection of the slow-growing mycobacteria. Methods of using the probes to detect and amplify Mycobacteria nucleic acid and kits containing the same are also disclosed.