BackgroundIn the past, clinical study participants have suffered from the experiments that they were subjected to. Study subjects may not understand the study process or may participate in clinical studies because they do not have access to medical care. The objectives of the present study were 1. to analyze the motives that might cause a volunteer to participate as a study subject; 2. to identify the social-demographic profile of this study subjects; and 3. to determine whether the motives to volunteer as a study subject are in accordance with the established legal and ethical principles for research in Brazil.MethodsMixed-methods research was used (a qualitative-quantitative approach). A sample of 80 volunteers underwent a semi-structured interview, which was based on a survey script that was elaborated from discussions with key informants. The sample was randomly selected from a database of clinical study volunteers that was provided by Brazilian clinical study centers. The interviews were recorded and transcribed. Descriptive statistics were used for content analysis, including contingency tables with hypothesis testing.ResultsThe motivations for clinical study participation were linked to types of benefit. The most frequently encountered motivations were financial gain and therapeutic alternative. Altruism was not a common motivator, and when altruism was present, it was observed as a secondary motivator. All participants reported that they understood the Informed Consent Statement (ICS). However, only two parts of the form were remembered by all of the volunteers: the section on being able to leave the study at any point and the section that stated that there would be some responsible professional at their disposal for the entirety of the study.ConclusionsThe present study shows that study participants are primarily motivated by personal benefit when volunteering to participate in clinical studies. Whether these study participants had an integral understanding of the ICS is not clear.