We discuss tuberculosis treatment outcome monitoring and the adherence of countries in the WHO European Region to modifications introduced in 2001 to enhance inter-country comparability. Outcomes for definite pulmonary tuberculosis cases were compared for cases reported in 2001 and 2000. Reporting was considered complete if 98% or more of cases originally notified had outcome reported. In both years, maximal period of observation was 12 months from start of treatment. In 2000, countries reported outcome as 'cured', 'completed', 'died', 'failed', 'defaulted', 'transferred' and 'other, not evaluated' for cohorts of new and retreated cases. In 2001, following changes, countries were also requested to monitor cases with unknown treatment history and two outcome categories were added--'still on treatment' and 'unknown'. Of 42 countries reporting outcomes in 2001, 74% (31) had nationwide, complete data, up from 50% (19/38) in 2000. Twelve of 21 countries that reported on observation period complied with that recommended. 'Defaulted' and 'transferred' were applied interchangeably with 'unknown'. Among new cases, 'still on treatment' was used by 15/31 countries (range: 1%-15%). 'Failed' was rarely recorded in western European countries (<1%). European tuberculosis outcome monitoring should include all definite pulmonary cases, applying the standard period of observation and revised categories, and preferably reported using individual data.