Introduction: Institutions have developed professionalism policies to help guide physician social media behavior in light of professionalism lapses that have resulted in serious consequences. Prior research has gathered perspectives on online professionalism; however, the public’s views remain poorly understood. Importantly, the impact of physician social media behavior on patient trust is unknown. Methods: To determine whether patients’ trust might change based on their physicians’ social media behavior, we conducted a cross-sectional survey across three U.S. cities (n = 491). The survey assessed patient trust using hypothetical scenarios. Results: Most respondents reported they would have less trust if their physician posted racist comments online, wrote a disrespectful patient narrative, appeared intoxicated in a photograph, or wrote profanity. Respondent age and education impacted change in trust. Conclusions: We conclude that physicians’ social media behavior may affect patient trust. Better understanding of how physicians’ online presence impacts their relationships with patients can help guide policy and inform educational efforts.