Aim of the work: to evaluate the detection rate and time of Mycobacterium tuberculosis by using the Bio FM system in comparison with the Lowenstein-Jensen medium. Patients and Methods: A Total 50 smear AFB positive sputum samples were included in this study and received from three groups: Group I:Thirty four (34) patients with fresh sputum smear + ve (New cases) Group II:Ten (10) Relapsed cases Group III: Six (6) Treatment failure cases all cases were exposed for Thorough history taking, Complete physical examination, routine laboratory tests including ESR, Plain chest X-ray- P.A and lateral view if needed ,Sputum smear for acid fast bacilli (Zeil Neelsen staining), Tuberculin skin test using Mantoux technique, ,Sputum culturing on Lowenstein-Jensen medium and Bio -FM medium. Results: The shortest mean detection times on the two studied isolation media were for the cases with far advanced lesion on chest X-ray. On Lowenstein Jensen, it was (17.50 days ± 6.802) and on Bio-FM it was (10 days ± 5.752).While the longest times were for the cases of minimal lesion, On Lowenstein Jensen, it was 24 days (±11.449) and on Bio-FM it was 15 days (±10.905).The mean detection times of moderately advanced cases on Lowenstein Jensen, it was 19.57 days (±9.086) and on Bio-FM was 12.65 days (± 8.074). Conclusion: Bio-FM showed greater superiority in detection time over Lowenstein Jensen with no significant difference between the two media in detection rate.