Increased chromosomal aberrations [CA] are regarded as a biomarker of personal exposure to dangerous chemical agents. Methods: Cytogenetic analysis was performed on 40 tuberculous [TB] patients [before and after receiving anti-TB drugs], to evaluate the possible genetic damage induced by Mycobaterium tuberculousis as well as by short term combined anti-TB drugs [pyrazinamide, rifampicin, INH & ethambutol]. For comparison, 40 controls were selected. Results: The frequency of CA in both TB patients groups [before and after treatment] showed a significant increase as compared to controls. The mitotic index was significantly decreased in both TB patients groups. Conclusion: TB infection by itself as well as the short term combined anti-TB drugs had a chromosome damaging effect on human lymphocytes in vivo. These drugs should be used with caution. Alternative drug combinations that are equally efficient but less harmful to the genome have to be selected. Cytogenetic analysis for detection of cases with CA [I.E., susceptible for progression of victims of mycobacterial or drug effects] should be advised to all patients especially in the child bearing age.