In this study we assessed the existing communicable disease surveillance system in health centers of a province in northeastern Thailand. The first part of the study was an examination of medical records from 11 local health centers: 649 were examined for sensitivity, positive predictive value, and representativeness; and 433 were examined for timeliness and data quality. The second part of the study looked at 50 local officers from 11 local health centers, 1 district health office, 1 community hospital, and 8 sub-district administrative organizations. Quantitative data was collected through a review of medical records. Qualitative data was collected by focus groups and in-depth interviews. The reporting of suspected cases was 50.8%. Sensitivity was low for common diseases. Positive predictive value was lowest for fever of unknown origin (0%). Data quality for the date of onset and diagnosis was low. Case reporting was considered timely in only 45% of cases. Health officers perceived the surveillance system as not being up-to-date. They only collected data in a district without data analysis; the information provided by the system is not representative of the true epidemiological situation countrywide and cannot be used to help monitor disease patterns and trends. In conclusion, health officers should report diseases according to symptoms and analyze data continuously to identify urgent problem and elicit prompt responses.