Background African Americans are consistently underrepresented in cancer clinical trials. Minority under‐enrolment may be, in part, due to differences in the way clinical trials are discussed in oncology visits with African American vs. White patients. Objective To investigate differences in oncologist–patient communication during offers to participate in clinical trials in oncology visits with African American and White patients. Methods From an archive of video‐recorded oncology visits, we selected all visits with African American patients that included a trial offer (n = 11) and a matched sample of visits with demographically/medically comparable White patients (n = 11). Using mixed qualitative–quantitative methods, we assessed differences by patient race in (i) word count of entire visits and (ii) frequency of mentions and word count of discussions of clinical trials and key elements of consent. Results Visits with African American patients, compared to visits with White patients, were shorter overall and included fewer mentions of and less discussion of clinical trials. Also, visits with African Americans included less discussion of the purpose and risks of trials offered, but more discussion of voluntary participation. Discussion and conclusions African American patients may make decisions about clinical trial participation based on less discussion with oncologists than do White patients. Possible explanations include a less active communication style of African Americans in medical visits, oncologists' concerns about patient mistrust, and/or oncologist racial bias. Findings suggest oncologists should pay more conscious attention to developing the topic of clinical trials with African American patients, particularly purpose and risks.