Context: Clinical trial is an experiment on comparable groups of human beings which evaluates the efficacy of a treatment or medical intervention by comparing the effects with other testing treatments or control treatments. Clinical trials help develop alternative treatment solutions or a preventative method for disease as well as support participants with medical and healthcare services during the trial period. Other benefits of clinical trials include gaining information, ensuring health issues, detecting early disease symptoms, and reducing medical services costs. Aims: To evaluate willingness to participate (WTP) in clinical trials (CT) in Ho Chi Minh city and examine the factors associated with it. Methods: A cross-sectional study was conducted through the online sampling method and gathered 581 valid responses during two weeks in February 2022. Results: Among 581 respondents, 71.6% stated they were willing to participate in CT, while 48.2% stated that they would let their family enroll. WTP in CT was higher in participants of younger age, single, not having children, healthy, and without chronic disease. Vietnamese age was associated with WTP in CT. Conclusions: Assessing WTP in CT helps state management agencies, organizations and research institutes design suitable CT models and increase the voluntary participation rate in CT.