Documentation on the TB situation in prisons in developing countries is limited, and very few studies have quantitatively evaluated TB control programmes in prisons. This study aimed to evaluate TB control in Mongolian prisons by analysing routine programmatic data. The TB caseload in prisons has significantly diminished in the last decade, synchronised with policy and programmatic development, including systematic entry screening on detention and after conviction, and improved living conditions. Improved case detection during entry screening may have contributed to the significant reduction of the TB caseload in prisons.