The Lowenstein-Jensen is an egg-based microbiology medium that was designed for selective isolation of Mycobacterium spp. The main inhibitory composition in this medium is a synthetic dye called malachite green. Mycobacterium spp. is resistant to the dye by de-colorization and oxidation of it. Some non-tuberculosis organisms may also overcome this inhibitoryingredient by similar enzymatic activity. In the final inspection of the bone TB culture of a teenage patient, the blind smear revealed the Pseudomonas talus osteomyelitis. Accordingto the present and similar experiences, the preparation of 1-2 blind smears from TB culturenegative specimens taken from sterile sites of the body may unmask mycobacteria with the atypical colony and non-tuberculosis microorganisms.