Introduction: Citizens of developing countries are often in vulnerable situations because of illiteracy, unfamiliarity with medical interventions, effects of war resulting in famine, and extreme poverty. The health-related conditions that arise out of these situations however make research in these populations vital and increasing funding for research on diseases that affect the world 's poor is making such research possible. The resulting tension between the need for research and the possibility of exploitation of participants' vulnerability, mandates the development of reliable ways of ensuring that participants' consent is voluntary, adequately informed and well understood. The Nuremberg Code emphasises the requirement of voluntariness in informed consent by insisting that participants should be able to exercise freedom of choice without the intervention of any element of force, fraud , deceit, duress, or other forms of constraint or coercion. Aim: This study assessed research participants' understanding and voluntariness of informed consent in a clinical trial. Methods: The study design was a cross-sectional analysis of the informed consent process. It consisted of qualitative and quantitative components. It was a cross-sectional survey of 75 research participants in a malaria clinical trial using questionnaires in the from of forced-choice check lists and patient self-report to assess voluntariness and understanding of informed consent. Data were analysed using SPSS V 17. Results: All the respondents involved in the clinical trial gave consent before they were recruited. The reasons for consenting to participate in the clinical trial ranged from the opportunity to get treatment (28%), opportunity for diagnosis of ailments (32%), to prevent illness (36%) and to receive information about medical care (4%). The major benefits participants attributed to taking part in the research were the opportunity to obtain treatment (59%), diagnostic tests (35%) and education (6%). Among the research participants, 10.7% believed that they should be paid for participation and about 8% felt that payment could influence their decision to participate because it could act as a motivation. They could however not proffer an amount that they would consider significant enough to influence their decision. There was no significant association between factors that influenced participation and age (p=0.533), sex (p=0.342), education (p=0.078), religion (p=0.144) and marital status (p=0.239). Almost all (98.7%) participants claimed that they had understood the information given to them during the consent procedure and they all gave consent without consulting anybody apart from the medical personnel.The majority of respondents - 74 (98.7%) - stated that they were not allowed to go home with the informed consent document, while 1(1 .3%) of the respondents said there was no need to go home with the informed consent document. In the assessment of understanding using the forced-choice checklist, however, only 37% understood issues concerning randomization of participants and only 28.8% understood issues about compensation for research related injury. Discussion and Conclusion: In this study, the voluntariness of participants was influenced by factors related to the benefits accrued through participation. The need for participants to make free and informed choices based on adequate information given by the investigator cannot but be emphasized as a right and not a privilege. In light of the limited understanding about randomization and injury compensation identified in this study, there is a need for additional protection of vulnerable populations. This could be in the form of allowing adequate time to enable the improvement of participants' understanding of the consent form, using innovative ways of explaining complex concepts such as randomization, and providing the necessary support to facilitate participants' right to self-decision, except when they are incapable of consenting. / Thesis (M.Soc.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.