Bacteriological diagnosis of tuberculosis is largely dependent on direct microscopy ofrnsputum smears. It is the most widely available diagnostic test, especially in developingrncountries where the other options are usually not practical due to the limited resourcesrnavailable. However, its sensitivity is not optimal when used in control programs, usuallyrnranging from 8.8% to 46.4% in most African laboratories. The sensitivity of therntechnique is further undermined in areas with high HIV prevalence. If sensitivity could bernimproved, the method has the potential to become an even more valuable tool forrnNational TB Control Programs. Treating the sputum with house bleach (NaOCl) has beenrnreported to increase sensitivity of direct microscopy. Therefore, the aim of this study wasrnto compare the diagnostic performance of the three different bleach methods reported sornfar: centrifugation, overnight sedimentation and short term bleach digestion (30 min),rnwith conventional direct microscopy and validate against culture as a gold standard on arngiven group of specimens. This cross sectional study was conducted at Awassa HealthrnCenter and Bushulo Major Health Center in Awassa. Five hundred (500) consecutive newrnTB suspects presenting at the health facilities during July to December, 2006 werernenrolled in the study. Direct smears were prepared and stained using Ziehl-Neelsenrntechnique and specimens were decontaminated and inoculated onto Lowenstein-Jensenrnmedia for culture. The left over sputum samples were pooled, equal amount of bleachrnwas added and then divided in three portions for the three bleach treatment techniques.rnSmears were prepared after centrifugation, overnight sedimentation and short termrndigestion. The direct and bleach treated smears were read blindly by two independentrnmicroscopists. Ten percent of the negative and 20% of all the positive smears werernretained for quality control. Smears were graded using the WHO/IUATLD scale.rnConsidering smears graded scanty (