Tuberculosis is an infectious disease caused by the bacillus Mycobacterium tuberculosis. The most common manifestation of the disease is pulmonary tuberculosis but other organs can also be affected (so called extra-pulmonary tuberculosis). Until the year 2005, the number of reported tuberculosis cases worldwide has been increasing. In Slovenia, in 1996, the control over tuberculosis patients was intensified and improved. A decline in morbidity was consequently achieved, with only 9.3 cases per 100,000 reported in 2009, which ranks us among the countries with very low tuberculosis morbidity. In Slovenia, tuberculosis is more common in men. Elderly, diabetics, alcoholics, nursing home residents, patients who previously recovered from tuberculosis, health care workers and people who have been in contact with infectious patient are all more likely to get the disease. In this article we present the case of an elderly woman who fell sick with uncharacteristic features of the disease and an uncharacteristic chest radiograph. Because of her elderly age and diabetes, she belonged among the group with a higher risk of contracting tuberculosis. The purpose of this paper is to demonstrate the performed investigations, diagnostic algorithm and principles of treatment of active pulmonary tuberculosis.