The number of clinical trials related to HIV/AIDS, tuberculosis and malaria conducted in Africa is increasing sharply and is expected to increase further in the coming years [1,2]. Routine health assessment and management of clinical trials relies on accurate laboratory references. Of primary importance in vaccine clinical trials is the evaluation of safety and tolerability in a clinically ‘‘normal’’ population. Furthermore, volunteers may be assessed for disease progression and evaluation of possible clinical trial-associated toxicity and adverse events. Laboratory reference intervals for healthy populations have not been established in most African countries. Common practice in these countries, including Mozambique, is to use reference ranges derived from populations living in Europe or the United States US). Studies have shown differences between clinical reference ranges in African populations compared to those established in industrialized countries [3–6]. Several studies have also reported that laboratory parameters vary geographically by ethnic origin, genetics, gender, altitude and environmental factors [3,4,7–9]. The use of improper clinical reference ranges to assess participant eligibility and safety for clinical trials may lead to unnecessary exclusion of eligible participants, contribute to overreporting of adverse events (AEs) [10] and increase the number of referrals for clinical investigations. Laboratory abnormalities based on non-indigenous laboratory parameters and medical abnormalities were reported to be the main reasons volunteers were excluded from two Kenyan HIV vaccine clinical trials [7]. Moreover, studies have suggested that use of the US NIH Division of AIDS (DAIDS) toxicity tables may not be appropriate for African populations [10,11]...