In order to search new candidates of pharmaceutical target, in vivo induced antigen technology (IVIAT) was used to screen in vivo induced (ivi) genes of Mycobacterium tuberculosis (M. TB). Genomic expression library of M. TB was first constructed with an inducible plasmid pKK223-8; the titer of the library was 1.02 x 10(5) CFU. Sera from ten tuberculosis patients were pooled and absorbed against in vitro-grown M. TB and Escherichia coli, and used to probe the genomic expression library. 16 positive clones were identified by immunological screen, including 22 ORF: two encoding lipid metabolism proteins, five information pathways proteins, two PE/PPE proteins, six intermediary metabolism and respiration proteins, one cell wall and cell processes protein, four conserved hypothetical proteins and two conserved hypothetical proteins with an orthologue in Mycobacterium bovis. Parts of these genes can be used as candidates of pharmaceutical target because they may be relate with virulence.