Background: Complete blood count (CBC) reference intervals were essential for effectivelyrndiagnosing diseases, measuring drug toxicity or side effects, disease staging and monitoring ofrnresponse to treatment, therapeutic management decision, or other physiological assessment in thernclinical laboratory and assessing overall health. They may also be used in clinical trials as arnguide to set inclusion and exclusion criteria. Factors such as genetics, dietary patterns, gender,rnage, ethnic origin, altitude, pregnancy, and geographical factors and geochemical andrnenvironmental pathogens were known to influence hematological reference intervals (RIs).rnHence, there is a need to determine locally relevant hematological reference intervals. rnObjectives: To determine hematological parameters reference intervals for apparently healthyrnpopulation aged 15 to 60 years in Addis Ababa. rnMethods: A cross- sectional community based study consisting 790 males and females (pregnantrnand non-pregnant) at household level was conducted from January to May 2019 in Addis Ababa,rnEthiopia.. A complete blood count (CBC) was performed using Sysmex XT1800i automatedrnhematology analyzer. The non-parametric test as per the CLSI guide was used to determine thern2.5th and 97.5th percentiles. SPSS-IBM version 24 statistical software was used for data entryrnand analysis. Differences among groups were tested and level of significanc was set at P valuernless than 0.05.rnResult: Males comprise 262, and 346 non-pregnant females and 182 pregnant women werernincluded. The 2.5rnthrn and 97.5rnthrn RIs determined were somehow inconsistent with the RI currentlyrnin use. RBC count, Hgb, HCT and MCHC were significantly higher in males than females whilernmedian value for MCV, MCH, RDW-CV and RDW-SD values were higher in females thanrnmales. Non-pregnant females had significantly higher median PLT count and PCT than malesrnand pregnant women. Pregnant women had significantly higher median PDW, MPV, P-LCRrnthan their non-pregnant counterparts and males. A decrease in RBC parameters and increase inrnWBC count was observed with increasing trimester.rnConclusion: As differences were noted with the company derived RIs and other populationrngroups, the current RI needs to be in use in Addis Ababa.