Abstract: Objective　To compare the results of sputum smear Gram staining microscopy with their culture results in 492 cases of sputum specimens in order to evaluate the clinical significance of sputum smear Gram staining microscopy.  Methods　A total of 492 sputum specimens were collected，and their characters and colors of sputum specimens were observed visually. The sputum smear Gram staining microscopy was performed. According to the results，the sputum specimens were classified into A，B and C categories，and were cultured for bacterial identification. The results of microscopy were compared with the detection rate of bacteria.  Results　There were 368 qualified sputum smear specimens in 492 sputum specimens. The qualified rate was 74.80%. There were 124 substandard specimens，accounting for 25.20%，and 426 bacteria were detected. The bacterial detection rate was 77.72% in the 368 qualified sputum smear specimens，of which 286 specimens detected 368 bacteria. The coincidence rate of the qualified sputum smear results and culture results was 71.19%. The bacterial detection rate was 35.48% in the 124 qualified sputum smear specimens，of which 44 specimens detected 58 bacteria. According to the visual observation，the qualified rates and bacterial detection rates of the mucus，bloody and purulent sputum specimens were relatively high，and that of the water or foam-like sputum specimen was low. The qualified rates and bacterial detection rates of the colorless sputum specimens were low in sputum specimens with different colors.  Conclusions　The sputum smear Gram staining microscopy is one of the most simple and cheapest rapid diagnosis methods of the respiratory tract infections. It results faster than culture，and can provide important information for patients in early diagnosis and treatment. The sputum smear Gram staining microscopy can screen out qualified sputum smear specimens and increase the bacterial detection rate of sputum culture. Therefore，sputum smear Gram staining microscopy has clinical significance.

Key words: Gram staining, Sputum smear, Bacterial culture, Sputum character, Sputum color