During the large Ebola outbreak that affected West Africa in 2014 and 2015, studies were launched to evaluate potential treatments for the disease. A clinical trial to evaluate the effectiveness of the antiviral drug favipiravir was conducted in Guinea. This paper describes the main challenges of the implementation of the trial in the Ebola treatment center of Guéckédou. Following the principles of the Good Clinical Research Practices, we explored the aspects of the community's communication and engagement, ethical conduct, trial protocol compliance, informed consent of participants, ongoing benefit/risk assessment, record keeping, confidentiality of patients and study data, and roles and responsibilities of the actors involved. We concluded that several challenges have to be addressed to successfully implement a clinical trial during an international medical emergency but that the potential for collaboration between research teams and humanitarian organizations needs to be highlighted.