Background: The Rrepublic of Moldova reports the biggest incidence of tuberculosis and the lowest success treatment rate among European region countries. In the most of patients the antituberculosis treatment failure is correlated with social risk factors (social, economical low status, social-epidemiological category of the population) and biological (young age, male sex, some physiological conditions, associated diseases). Clinical factors (extensive forms, chronic evolution, immune disturbances), therapeutical factors (treatment errors and interruptions, individualised regimens) and administrative factors (interrupted supplying, suboptimal drug quality) prevail in regions with defficiencies in heath care delivery. Risk factors association is more evident than the severity of one risk factor. Clinical and immunological assessement is important before initiation of the treatment for establishing risk reduction measures and increasing success rate. Material and methods: The study was conducted on 201 cases with treatment failure and 105 with successfuly ended treatment. Cases were investigated according to national standards and local specific immune procedures. Results: High clinical risk factors were revealed: late detection, extensive and bilaterally localised tuberculosis, lung tissue destructions and dissemination, complications, comorbidities; as well as high immune risk factors were established: low cellular resistance, high degree of intoxication, low preimmune resistance. Conclusions: The study at least of high clinical and immune risk factors must be performed before the treatment initiation for increasing the treatment success rate.