Introduction: The attitudes and opinions of participants can influence their recruitment and retention in research. We described participants’ experiences and knowledge of their engagement in clinical trials, the reasons for participation, roles and obligations, perception of risks, confidentiality, protection, and respect of their rights. Methods: This was a cross-sectional study which employed mixed methods to collect data on trial participants’ experiences and knowledge of their engagement in clinical trials in Uganda. We used a researcher-administered structured questionnaire to collect quantitative data. Descriptive statistics and quotes were used to summarize the study findings. Results: A total of 418 clinical trial participants were surveyed and these included 66.0% female, median age was 29 (interquartile range: 23-37) years. 76.6% had participated in one clinical trial in the past five years. 4.6% were involved in 2 or more clinical trials at the time of the study. 74.6% and 71.3% knew their roles and rights respectively while 97.9% said the trial was beneficial to them. Of those who knew their role, 74.4% said their role was to adhere to treatment. 68.1% knew they had a right to withdraw from the study any time while 11.1% knew their right to know the treatment groups. 5.0% said their rights were violated. Qualitative findings revealed that; treatment and access to free medical services such as ‘whenever my child falls sick I do not foot the treatment bills (FGD female trial participants), need to volunteer, altruism, better health, transport, money and in-kind benefits were great motivations to participation. Conclusions: This study revealed that communities’ attitudes and experiences of engaging in clinical trials influence their choice to or not to participate in trials. It is recommended that, community engagement should be conducted before, during and after the study, so that participants appreciate their roles, rights, benefits and risks related to their participation.