Abstract: Objective To understand prevalence of smear negative pulmonary tuberculosis and its discovery situation before and after implementing the tuberculosis control program, to analyze the causes of existing problem and importance ofimproving smear negative case finding. Methods Data was obtained fromlocal registration information of pulmonary tuberculosis cases and tuberculosis epidemiology survey as well as from internet based Chinese infectious reporting system in Tongliao City from 2005 to 2008.Results According to four times of tuberculosis epidemiology survey, the prevalence rate of smear negative pulmonary tuberculosis is higher than that of smear positive, and accounted for two third of number of active pulmonary tuberculosis. From 1991 to 2003, the ratio of smear negative to smear positive stabilized between 1.1 to 2.4. However, from 2004to 2008, the registration number of the new smear negative and positive pulmonary tuberculosis cases both increased year by year, the ratio of smear negative to smear positive decreased to 0.60～0.85. This result is significantly different in comparison with the Results of epidemiology survey. Conclusion Since 2004,there was an obvious imbalance in terms of number of smear negative to smear positive detected; Registration rate of smear negative cases was relatively low. Therefore control work of smearnegative tuberculosis should not be overlooked while we emphasis smear positive case finding.

Key words: tuberculosis, pulmonary/ epidemiology, pulmonary/ prevention &, control, Tongliao city