Abstract rnBackground: Hematological reference intervals (RIs) are important in routine assessments for therndiagnosis of blood disorders, infectious diseases, immune diseases, diseases progression and assessmentsrnof ant-retroviral treatments. However, most of Africans including Ethiopia use RIs which are adoptedrnfrom textbook, manufacturer of machines or Western countries while several factors are affecting thesernparameters. rnObjective: To establish hematological reference intervals for apparently healthy adult men and pregnantrnwomen at Arbaminch, Southern, Ethiopia, 2020/21. rnMethods: A cross-sectional study design was applied from Nov 2020 to Sep 2021. A systematic rnsampling technique was used to recruit a total of 312 men and pregnant women aged 18 years and above.rnIndividuals who are apparently healthy(fulfill the eligibility criteria) and are voluntary to participate in thernstudy were included. A structured questionnaire was used to collect data about socio-demographic, healthrnstatus, drug usage, and nutritional habit of the participants after getting the ethical clearance. Thernlaboratory specimens (blood, urine, stool) were collected according to standard operating proceduresrn(SOPs) and the laboratory investigation was performed. Quality control material for hematological testsrnwas used according to the SOPs. Age and sex specific 2.5rnthrn and 97.5rnthrn reference interval was determinedrnusing the non-parametric method. Data were entered and analyzed using SPSS version 23.0 software. rnResults:- The median and 95% RI for RBC parameters were, 4.92(4.32-5.79)*10rn/L, 14.8(13.217.08)g/dlrnrnand 45.2(41.3-54.18)% for RBC, Hgb and Hct respectively for adult men and 4.39(3.565.16)*10rn12rn/L, 13(9.3-15.9)g/dl and 41(32.6-46.2)% for RBC, Hgb and Hct, respectively for pregnantrnwomen. The median and 95% RI for WBC parameters and platelet count were 7.5(4.14-11.5)*10rn2.2(1.2-5.21)*10rn9rn/L, 0.7(0.3-1.2)*10rn9rn/L, 4.8(2.06-7.88)*10rn9rn/L, and 227(152-353.3)*10rn/L WBC count,rnabsolute lymphocyte, absolute mixed cell and absolute neutrophil and platelet count for adult men andrn7.5(4.55-12.4)*10rn9rn/L, 2.2(1.2-3.9)*10rn9rn/L, 0.7(0.3-1.2)*10rn9rn/L, 4.9 (1.9-10.1)*10rn/L and 202(142362)*10rn9rn/L WBC, Lymphocyte, Mixed cell, Granulocyte and platelet count for male and pregnantrnwomen, respectively. rnConclusion:- The result from the current study identified that there is variation in most of the referencerninterval of hematological parameters especially red cell parameters with reference intervals conducted in rnother parts of the country, Africans as well as western countries.