Objective: To determine HIV seroprevalence among tuberculosis patients and the burden of HlV attributable tuberculosis among notified patients in Kenya.Design: A cross-sectional anonymous unlinked HlV seroprevalence survey.Setting: Tuberculosis diagnostic clinics of the National Leprosy Tuberculosis Programme in 19 districts.Subjects: One thousand nine hundred and fifty two newly notified tuberculosis patients.Interventions: Selection and registration of eligible subjects followed by obtaining 5ml of full blood for haemoglobin testing and separation of serum for HIV testing by ELISA.Main outcome measures: HlV seroprevalence per district and burden of HIV attributable tuberculosis among tuberculosis patients.Results: A total of 1,952 eligible patients were ended. The weighted seroprevalence in the sample was 40.7% (range 11.8-79.6% per district). The seroprevalence was significantly higher among females and patients with sputum-smear negative tuberculosis. Chronic diarrhoea, female sex, oral thrush and a negative sputum were independent risk factors for HIV infection. The Odds ratio for HIV infection in female tuberculosis patients aged 15-44 years, was 5.6 (95% CI 4.5-6.9) compared with ante-natal clinic attenders. The population attributable risk was 0.22 in 1994.Conclusion: The HlV epidemic has had a profound impact on the tuberculosis epidemic in Kenya and explains about 41% of the 94.5% increase of registered patients in the period 1990-1994 and 20% of all registered patients in 1994. Repetition of the survey with inclusion of a more representative control group from the general population may provide a more accurate estimation of the burden of HIV attributable tuberculosis