An epidemiological and clinical study of tuberculosis in a district with a population of 100 000 has been in operation in Czechoslovakia since 1960. Its objective is to ascertain the epidemiological situation and long-term trend in respect of tuberculosis in a country with well-established tuberculosis control facilities. This second report presents the results achieved in the period 1965-72 and the epidemiological trend of tuberculosis observed during the 12-year study period. The fundamental control measures adopted during the study included systematic BCG vaccination of the newborn and revaccination of persons aged 14 and 19 years; mass surveys of the population over 14 years of age by photofluorography; case-finding among persons with symptoms and in risk groups; systematic treatment of all persons with active tuberculosis-i.e., supervised inpatient treatment followed by outpatient self-administered regimens; and radiological and bacteriological follow-up of cases.The results confirmed that the systematic application of effective treatment throughout the study population was followed by a rapid decline in the prevalence of bacillary tuberculosis, particularly in its chronic form. The incidence of bacillary tuberculosis declined more slowly, because the risk of contracting the disease continued to be high for middle-aged and elderly persons. Indiscriminate photofluorographic surveys of the study population at 3-yearly intervals produced a decreasing yield.An increasing proportion of noninfected persons among the population is the basic condition for a further decline of tuberculosis. The cost of tuberculosis control can be reduced by strict adherence to rational and economical working methods. Most of the economic indicators analysed fell to less than one-fifth between 1961 and 1972.