Abstract Background Older people experience multiple barriers to enrolment in clinical trials. Caregivers play an important role in supporting patients with Parkinson’s disease. Understanding the experiences of patients and caregivers who participate in trials is important to inform the design of future studies and identify problems with recruitment and retention. Objective To systematically review and synthesize qualitative studies exploring the experiences of participating in clinical trials from the perspectives of patients with Parkinson’s disease and their caregivers. Methods Two reviewers independently searched the following databases: MEDLINE, Embase, PsycInfo, Cochrane, and CINAHL. The reference lists of all selected papers were screened for additional studies. Articles meeting predefined eligibility criteria were included in the synthesis. Methodological quality of each study was assessed using the Critical Appraisal Skills Programme (CASP) Qualitative Checklist. Included study findings were synthesized using the principles of thematic analysis. Results Eleven studies were included. Five key themes were identified: positive experiences of participating in research, assessment completion, motivators, enablers, and barriers. Positive experiences of participating in studies were linked to social interaction with other patients, building trust with the researchers, and expertise of the research team. Conclusions This review supports literature highlighting the important role of caregivers in supporting patients with Parkinson’s disease. Future studies are needed to further examine their perspectives on participating in research.