Background: Complete blood count (CBC) and differential white cell counts are the mostrncommonly ordered tests in clinical practice. The standard operation procedures in the ARTrnlaboratories, which are prepared based on the instrument instruction manual of the company,rnrecommend 8 hours storage at room temperature. However, there is no clear information as tornhow to handle delayed specimens in situations where delayance is unavoidable.rnObjective: To evaluate whole blood stability with time, storage temperature andrntransportation conditions using Cell-Dyn 1800, a 3-part diff hematological analyzer.rnMethods: A total of 45 adult participants, 19 from ART clinic of Tikur Anbessa SpecializedrnHospital and 26 apparently healthy Medical Laboratory Science students of Addis AbabarnUniversity were included in the study using convenient sampling methods. EDTA wholernblood samples were analyzed at baseline before and after aliquoting. Each of six aliquots, forrnroom temperature and 2-8rnOrnC storage, one each for transporting with and without an ice boxrnwere used. After the baseline analysis of the direct EDTA tube and an aliquot, all specimensrnwere analyzed at 8, 24, 32, 56 and 72 hours of storage. Same EDTA tube was used each timernafter refrigeration. Transported samples were analyzed within 8 hours and compared withrnbaseline values. Cell-Dyn 1800 automated hematology analyzer was used following thernmanufacturers instruction.rnResults: Among the CBC parameters, WBC, RBC, Hgb, MCH were stable for 72 hours postrnsample collection regardless of storage temperature. These values were also unaffected duringrntransportation. MCHC was relatively less stable. PLT counts remained stable in the direct EDTArntube samples stored at 2-8rnOrnC for 72 hours while aliquoted samples were less stable, showing arndeclining trend with time. The MCV and RDW, parameters affected by change in the red cellrnsize showed an increasing trend with time where differences were statistically significantrn(P