Repetitive element polymerase chain reaction (PCR) typing was applied to two Mycobacterium tuberculosis isolates for which both viable and nonviable cultures were available. DNA extracted from the nonviable cultures and from fresh subcultures of the viable cultures was amplified with primers directed against the insertion sequence IS6110 and the polymorphic GC-rich repetitive sequence. For both isolates, the nonviable cultures generated PCR-banding patterns identical to those generated by the fresh subcultures.