Background : Air originated contaminating bacteria can interfere the precision of clinical bacteriology sample check. Ultraviolet tube can be used to avoid bacteriology laboratory check from contamination especially microbiology laboratory. The we of ultraviolet tube has an advantage in which it still can be used while in the process of reducing the number of bacteria in the air. Objectives of study : This study is a pre-experimental study with one group pretestpostest design. The object of the study was the air of bacteriology laboratory and subject of the study were grown bacteria in PCA media. This study was executed 16 times repetition before and after the use of ultraviolet tube. The obtained data were analyzed statistically by using parametric test, that is paired sample t – test with confidance interval is 95%. The analyzing data was used SPSS 16.0 for windows. The result of study : The average of the number of bacteria in the air before using ultraviolet tube is 292 CFU/m3 and after using ultraviolet tube is 31 CFU/m3. The everage percentage of the number of bacteria reduction after using two ultraviolet tube is 84 %. From paired sample t-test, it was obtained Asymp sig (2-tailed) as many as 0,000. Conclusion : There is significant difference between the number of bacteria in the air before and after using ultraviolet tube in laboratory in Analis Kesehatan Major Keywords : The number of bacteria in the air, ultraviolet tube, laboratory