Background: Several barriers face physicians with their participation in clinical trials.Aim of Study: To identify barriers to physicians’ participation in clinical trials.Methods: An analytical cross-sectional design was followed during October-December 2019. The study included 142 clinicians in Al-Hada Military Hospital, Taif City, Saudi Arabia. A self-administered questionnaire was constructed for data collection. It consisted of personal characteristics and 24 statements about possible barriers against participation in clinical trials. Results: Most participants (71.8%) were willing to participate in clinical trials, while 57.7% never participated in any clinical trials. Previous participation in clinical trials was significantly higher among non-Saudi than Saudi physicians (62.5% and 34.3%, respectively, p=0.002); it was more among consultants and specialists than residents (65.7%, 48.3%, and 29.5%, respectively, p=0.001); and it was significantly higher among physicians with more experience in clinical practice (p<0.001). Multivariate binary logistic regression model revealed that physicians’ age group, position, and willingness to participate in clinical trials were significantly associated with their previous participation in clinical trials (p=0.013, p=0.011, and p=0.010, respectively). The main barriers against physicians’ participation in clinical trials were the absence of motivation or encouragement to participate in clinical trials (78.9%), lack of training in clinical trials (77.5%), the long time required to conduct clinical trials (70.4%), and the lack of free time (69%). Conclusions: The majority of clinicians in Al-Hada Military Hospital, Taif City, Saudi Arabia were willing to participate in clinical trials. However, most of them, especially Saudi and those with less experience in clinical practice, did not participate in clinical trials. There were several barriers against physicians’ participation in clinical trials, such as the absence of motivation or encouragement to participate, lack of training, the long time required to conduct clinical trials, and the lack of free time.