234 isolates of Mycobacterium tuberculosis obtained from 1000 suspected cases of tuberculosis reporting at National Institute of Communicable Disease, Delhi for laboratory investigation between Jan 2001 to August 2002 were subjected to invitro drug sensitivity test against the first line drugs (Isoniazid, Streptomycin, Rifampicin, Ethambutol and Thiacetazone) by proportion method using Lowenstein Jensen (LJ) media. Out of 234 isolates of Mycobacterium tuberculosis, 142 were from cases of untreated tuberculosis, whereas only 92 isolates were from treated cases of tuberculosis. An initial drug resistance of 21.83% was seen against INH, 9.85% against Streptomycin, 15.49% against Rifampicin, 4.22% against ethambutol and 2.11% to thiacetazone. Multidrug resistance (MDR-i.e. Resistance to both INH and Rifampicin) was seen in 11.97% of isolates. 4(2.8%) isolates were found to be resistant to all drugs tested. A much higher level of acquired resistance was seen the figures being 61.95% for INH, 53.36% for rifampicin, 35.86% for streptomycin, 20.65% for ethambutol and 10.86% for thiacetazone. Avery high acquired MDR to the tune of 42.39% was seen. 24(26%) isolates were found to be resistant to all drugs tested. No significant difference were observed in the drug resistance pattern between pulmonary and extrapulmonary cases of tuberculosis in both initial and acquired drug resistance category.