The causes of the maintained endemia of tuberculosis in the area of the "Hospital Arnau de Vilanova", Valencia, were studied in 162 cases treated over a 6 year period. The social conditions of the area, predisposition factors and the rare clinical and radiological first manifestations are factors influencing the maintained endemia. The introduction of invasive diagnosis techniques to confirm the disease, brought about the diagnoses of cases that with the standard techniques would have been impossible, giving the false impression of a higher incidence. We concluded that it is necessary to keep the disease in mind in the differential diagnosis of risk groups, maintaining the required epidemiological measures.