Our aim was to describe the frequency of HIV infection among patients with tuberculosis and compare their characteristics with patients with TB but not infected with HIV. Patients with cough >3 weeks duration attending 8 hospitals in Abuja, Nigeria were screened with smear microscopy and culture and tested for HIV. Chest X-rays were graded by 2 readers. 731 (62%) of 1186 patients had positive cultures and 353 (48%) of these 731 patients were smear positive. 1002 (85%) patients were tested for HIV and 546 (55%) were positive. 53% (329/625) of the culture positive patients and 58% (217/377) of the culture negative patients were HIV positive. Anorexia, weight loss, low BMI (<18.5), haemoglobin (<11 gm/dl) and albumin and high ESR and liver enzymes were more frequently observed among patients with TB coinfected with HIV than in patients without HIV. Coinfected patients had less cavitations and lung involvement on X-rays than patients without HIV. In conclusion, the prevalence of HIV is very high among patients with TB in Abuja, Nigeria. The presence of HIV decreases the sensitivity of smear microscopy and complicates the diagnosis of TB. Selected clinical and laboratory parameters could be used to identify individuals with TB who are likely to be coinfected with HIV.