Background : Tuberculosis in the elderly is an increasing public health problem. Aim: To describe the epidemiological, clinical and microbiological characteristics of tuberculosis in patients over 65 years old, as compared to younger patients. Material and methods: We reviewed the case histories of tuberculosis, microbiologically diagnosed by Ziehl-Neelsen/auramine smear and Löwenstein-Jensen culture, in patients over 65 years old, in the sanitary area of Cadiz (Spain). Results: We detected 49 new cases (37 males) of tuberculosis in elderly subjects. The infection rate in this age group (16.3/100.000 inhabitants) is lower than in people younger than 65 years old (21.1/100.000 inhabitants). The most common symptoms were cough (44.9%), fever (40.8%) and dyspnea (44.9%). Neither of them were infected by the human immunodeficiency virus nor were parenteral drug abusers. Thirty seven percent of cases had a history of previous tuberculosis, and in 75.5% the disease location was pulmonary. The Ziehl-Neelsen/auramine smear was negative in 53.1% of the samples. Conclusions: The number of patients older than 65 years old with tuberculosis has increased in the sanitary area of Cadiz (Spain). This group of patients shows different epidemiological and clinical characteristics than younger patients (Rev Méd Chile 2004; 132: 325-30).