SETTING: Khartoum, Gazira and camps for displaced peopleOBJECTIVES: To find the extent of anti-tuberculosis drug resistance in Sudan and to estimate the association between drug resistance-TB and proportion of new cases and previously treated cases. And to identify medical, social and demographic factors associated with the development of drug-resistant TBDESIGN: Strains isolated from 144 patients with pulmonary tuberculosis were studied for susceptibility to anti-tuberculosis drugs by the BACTEC method. Data collection forms were filled, to identify factors associated with drug resistance.RESULTS: Twenty-seven strains (50%) were resistant to at least one anti-tuberculosis drugs. Thirty-one (22%) were multi-drug resistant. With exception of only 2 cases, all MDR were found among previously treated cases. The highest rate of mono-drug resistance was observed for streptomycin in both groups of patients (new and previouslytreated patients). 22 (23.6%) strains collected from new and 8 (15.6%) of strains collected from previously treated patients were resistant to streptomycin respectively. Resistance to ethambutol was only seen in multi-drug resistance strains. With the exception of only one strain, all strains resistant to rifampicin were multi-drug resistant. In Khartoum 24 (26.4%) were multi-drug resistant, in Gazira 4 (16%) and in the camps for displaced people 3 (10.7%) were multi-drug resistant. A history of previous treatment for tuberculosis, being more than 40 years of age, having long duration of symptoms, low weight and household contact of a TB patient weresignificantly associated with resistance to at least one anti-tuberculosis drug and multidrug resistance.CONCULUSIONS: There is a high prevalence of M. tuberculosis strains resistant to streptomycin also in new patients; drug resistance except for streptomycin among new cases is a rare phenomenon in Sudan, which indicates a low rate of transmission of resistant strains. Drug resistance among previously treated patients is present at an alarming level.