An attempt has been made in this study to isolate A identifyrnthermoduric A psychropivilic bacteria, which are the most seriousrnspoilage organisms, from milk obtained from tin? Addis Ababa OairvrnHovelpoment Enterprise (AADDE ). An effort was also made to trace thernsources A origin of these organisms so as to prevent or at least reducerntheir access into milk A hence increase the shelf -life of thernpasteurized milk A milk products.rnThe standard plate count { SPG) ranged between 4 X 10? Arn3 X 109 bactoria/ml for raw milk, between 6 X 10'* A 3 X 10^ for plantrnpasteurized milk A between 3 X 103 A 2.5 X for laboratoryrnpasteurized milk. The high standard plate count for the plantrnpasteurized milk, as compared to that of the laboratory pasteurizedrnmilk, has been found to bo due to the ability of many organisms to gainrnaccess to the pasteurized milk as post pasteurization contaminants.rnPsychrophilic bacteria wore the most dominant organisms inrnboth raw (98.1%) A plant pasteurized (53.0%) milk samples. Laboratoryrnpasteurized milk, on the other hand, contained predominantlyrnthermoduric bacte.rnDuring the course of study, bacteria belonging to 14 generarnwere isolated, the most dominant being: Streptococcus ( 27% ) ,rnStaphylococcus (19,5%), micrococcus (13.9%) , Bacillus ( 12.9%) ArnArthrobactor (11.3%),.rnOut of the 185 representative isolates identifiedrn50% were cocci A 40% rods.rnAs many as 16 species of bacteria belonging to 9 genera werernisolated from raw milk, while 20 species of bacteria belonging to 14rnrngonora wore isolatcd from tho plant pasteurized milk. This indicatedrnthat bacteria , other than those found in raw milk have been introducedrninto the pasteurized milk as post pasteurization contaminants from thernbulk tanks, fillers A their pipelines and the plastic bags that containrnpasteurized milk. This fact has also been supported by data fromrnkeeping quality tests performed at different sampling sites.rnSodium hydroxide ( dnOH ) A sodium carbonate ( NaC'03) , chemicalsrnrnregularly used for rinsing A disinfecting utensils at the Addis Ababarnhairy development Enterprise , were found to be ineffective inrninactivating bacteria at concentrations as high as 1:100 at 50-90rnminutes holding time. Other disinfectants tested such as Savlon , ArnChlorox, on the other hand, were found to i> effective in eliminatingrnthe same group of bacteria at lower concentrations ( 3 :HOO ) at 15-30rnminutes holding time.rnBased on this study , therefore, recommendations are made byrnwhich the Dairy Plant can improve milk handling A processing conditionsrnA produce milk A milk products with improved shelf -life.