Background: Smear forms (BK) should provide some crucial patient's information that permits the laboratory to select the appropriate bacteriological techniques for each case, a process that would fail if such information was inaccurate or omitted. Objective: To evaluate the quality of information contained in BK forms sent to laboratory for individual's diagnosis or treatment monitoring of tuberculosis (TB) in the Chilean Health Services. Methods: Descriptive study based on secondary data of all forms of smear-positive (BK+) in 2012 (n = 232) obtained from the population allocated to the South Metropolitan Health Service. BK+ forms were matched to BK+ cases handled in the TB program to assess the validity or omission of information on treatment situation (previous or current) and the current follow-up time. Results: Diagnostic BK were 62.9% (16.4% with previous treatment); of these 74.7% correctly reported a history of TB treatment but in patients previously treated the percentage falls to 66.7%. Among those under treatment control 26.7% were classified as previously treated and 43% did not recorded the follow-up time. Discussion: BK forms omit or incorrectly recorded fundamental information that should lead the laboratory procedures. As the finding of TB involves each and every one in the health personnel, we recommend continuous training stressing the inclusion of treatment's history and risk factors while the forms should avoid ambiguity.