Tuberculosis, one of the oldest diseases of human beings, has still high mortality rates. In this prospective study, 113 HIV seronegative patients with extrapulmonary tuberculosis (EPT) who were admitted to our department between January 2001 and July 2006 have been evaluated and cases with severe or mild forms of EPT have been compared with respect to epidemiological and clinical features, laboratory results and treatment outcomes. The age range of the patients were 16-78 years old (mean age: 46.3 +/- 16.9 years), and 64 of them (56.6%) were female. Severe and mild forms of EPT were diagnosed in 49 (43.3%) and 64 (56.6%) of the patients, respectively. The most frequently involved organ was detected as lymph nodes (43.3%), followed by pleura and vertebrate involvements with the rates of 12.4%. There was an underlying disease in 35 (30.9%) of the patients (diabetes mellitus in 15%; chronic renal dysfunction in 11.5%; malignancy in 4.4%), history of passed tuberculosis infection in 13 (11.5%) and history of contact with a tuberculosis patient in 25 (22.1%). In direct microscopic examination, samples from 19 (16.8) patients were found positive for acid-fast bacilli, and samples cultivated in Lowenstein-Jensen media yielded mycobacterial growth in 25 (22.1%) patients. The diagnosis have been made histopathologically in 89 (78.7%) of the cases. In comparison of the patients with severe and mild forms of EPT, the severe form were detected more frequently in males (p = 0.01), the positivity rates of culture and acid-fast staining were higher in patients with severe form (p = 0.0004 and p = 0.001, respectively). The mortality rate was also found higher in patients with severe form (p = 0.046). The cases who were diagnosed as EPT have been treated by three or four antituberculosis drugs. Izoniazid (300 mg/day, 6-12 months), rifampicin (600 mg/day, 6-12 months), ethambutol (1500 mg/day, 2-4 months), pyrazinamide (2000 mg/day, 2-4 months) and streptomycin (1 g/day, 45-60 days) were used for the therapy. Side effects due to the therapy were observed in 13.3% of the cases (most frequently; gastrointestinal intolerance in 53.3% and hepatitis in 40%), however, there was no necessity to quit the therapy. Surgical treatment has been applied in 14 (12.4%) of the patients. As a result, the investigation of epidemiological and clinical characteristics of extrapulmonary tuberculosis on the large series of cases may be essential for early diagnosis and treatment in endemic countries such as Turkey.