Abstract:
The Knowledge of distribution of ABO and Rh blood groups is helpful for effective 
management of blood banks and safe blood transfusion services. The frequency of these blood 
groups varies worldwide and may not be found in equal numbers even among ethnic groups. 
The aim of this study was to find out the distribution of ABO and Rh (D) blood groups among 
students attending Chorora Secondary and Preparatory school in West Hararghe Zone 
Oromio Ethiopia. The study was designed  from January–March 2020 in the laboratory of 
study area..  Blood samples were taken from 422 (N = 422) volunteer students from finger
pricks and blood  groups were determined on open slide by haemagglutination method using 
commercially available anti-sera A, B, and Rh (D). Descriptive statistics was used to 
calculate percentage frequencies of blood phenotype,The genotypic and allelic frequencies of 
the blood groups were calculated from the observed phenotypes under the assumption of 
Hardy–Weinberg equilibrium. In the ABO blood grouping  system, type O was the most 
prevalent (39%) followed by A (32%), B (23%) and AB the least (4.5%), in the pattern O > A 
> B > AB.  Most of the students were found to be Rh+ (95%) and Rh- 4.5.   Regarding the 
combined ABO/Rh blood groups, O+ was the most prevalent (161), A+ (129), B+ (93) and 
AB+ (18) and A- was also the most frequent 9(2.13%) B- 5(1.18%) and AB- 1(0.24%)  among 
Rh-negative students. The allelic frequencies of O (r), A (p) and B (q), D and d were 0.3957   
0.6291, 0207, 0.1500, 0.7768 and 0.3468, respectively.  Genotypic frequency of IOIO was the 
most (0.3957) frequent while that of IBIB was the least (0.0232) while DD and dd were  and 
0.6034,0.2232 respectively. The observed and expected frequencies of individuals having 
ABO and  Rh blood were not significantly different in both blood systems (goodness-of-f= 1 
and χ2 for Rh = 7.6x10-12  , df = 1; P < 0.05). The present study gives vital information 
regarding the management of blood bank and transfusion services in the study community. 
These study was first document in the study area and evidence for other person who wants 
making research on phenotypic and genotypic frequency of  ABO and Rh(D) blood system .