Research Paper (postgraduate) from the year 2009 in the subject Health - Public Health, ( Atlantic International University ), language: English, abstract: A total of 750 blood samples were collected into the dipotassium – ethylene diaminetetra – acetic acid (EDTA) tubes and BD vacutainer tubes from the population of Porto Novo at random ranging from 2 years to 70 years of age. The ABO blood group systems were tested on the samples by the forward and reverse technique of blood grouping by tube method. A total of 320 individuals were shown to be blood group O (43%), the blood group A were shown to be 226 individuals (30%), blood group B were 167 people (22%) and blood AB finally were 37 people making up to 5% of the population tested. This work follows almost the same discovery made by other researchers of ABO grouping system and did not show a significant differences among the groups except in that reported on Brazilian Indians in Mato Grosso which registered 100% blood group O among Indians of Mato Grosso by Bier at al(1982). The work serves as a fundamental screening on the distribution of ABO blood group system in Porto Novo and did not indicate whether there exists a difference of ABO blood group system distribution among other islands of Cape Verde and also a reference point for those engaged in clinical blood use like the red cross organisation and paramedical units who at times give blood on emergency basis.