"Two-assay" tests (TAT), immunoenzymatic determination of both specific antibodies and mycobacterial antigens in sera of tuberculous and non-tuberculous subjects, was undertaken in our territorial conditions, where BCG vaccination is systematically applied and the prevalence of tuberculous infection is relatively high. The sensitivity of the method, calculated on 42 patients with active pulmonary tuberculosis and on 39 patients with post-tuberculosis syndromes is high, i.e. 0.952. The specificity of the method separately calculated for 44 young subjects (under 21 years old), for 78 healthy adults and for 201 lung diseased patients, bacteriologically not ascertained as tuberculosis at the moment of sera prelevation, varied between 0.830 and 0.489. "TAT", performed with crude immunologic reagents, produces false-positive reactions in early BCG vaccinated subjects. Method specificity low values in pulmonary non-tuberculous patients group may be partially explained by the difficulty in establishing the real relationships, in time, between host and mycobacteria, by the bacteriological method imperfections or sample prelevating methods. Our results certainly underestimate the diagnosis value of "TAT".