Background. Pulmonary tuberculosis (TB) is a major health problem worldwide. Detection of the most infectious cases of tuberculosis - sputum smear-positive pulmonary cases - by passive case finding is an essential component of TB control. The district of Sidoarjo in East Java reported a low case detection rate (CDR) of 14% in 2003. We evaluated the diagnostic process for TB in primary health care centers (PHC) in Sidoarjo district to assess whether problems in identification of TB suspects or in diagnosing TB patients can explain the low CDR. Methods. We performed interviews with the staff (general nurse, TB worker, laboratory technician, and head of health center) of the 25 PHCs of Sidoarjo district to obtain information about the knowledge of TB, health education practices, and availability of support services for TB diagnosis. The quality of the laboratory diagnosis was examined by providing 10 slides with a known result to the laboratory technicians for re-examination. Results. Eighty percent of the nurses and 84% of the TB workers knew that cough >3 weeks can be a symptom of TB. Only 40% of the nurses knew the cause of TB, few could mention complications of TB and none could mention the duration of infectiousness after start of treatment. Knowledge of TB workers was much better. Information about how to produce a good sputum sample was provided to TB suspects by 76% of the nurses and 84% of the TB workers. Only few provided all information. Fifty-five percent of the 11 laboratory technicians correctly identified all positive slides as positive and 45% correctly identified 100% of the negative slides as negative. All TB workers, one general nurses and 32% of the laboratory technicians had received specific training in TB control. There has been no shortage of TB forms and laboratory materials in 96% of the PHCs. Conclusion. The quality of the diagnostic process for TB at PHC in Sidoarjo district should be improved on all levels. Training in TB control of all general nurses and the laboratory technicians that have not received training would be a good first step to enhance diagnosis of TB and to improve the case detection rate.