Plain language, either written or spoken, is associated with higher-quality communication in healthcare settings, but little research has focused on plain language and clinical trial discussions. The objective of this study was to describe physicians’ use of plain language during interactions in which patients were invited to participate in cancer clinical trials. Video-recorded clinical interactions, accompanying transcripts, and self-reported demographic data were taken from a larger study of communication and clinical trials (PACCT). Interactions (n=25) were selected if they included an explicit or pending invitation to participate in a clinical trial. We conducted a qualitative discourse analysis of transcripts. We excerpted all mentions of clinical trials and then inductively coded the excerpts to identify physicians’ plain language strategies. The analysis revealed five plain language strategies used by physicians. First, physicians used lexical simplification to replace medical terminology with simpler alternatives, such as replacing “combination study” with “add a second pill.” Second, they used patient-centered definitions to differentiate medical terminology from similar concepts, such as clarifying the differences between remissions and cures. Third, they used metaphors to connect medical terminology with familiar concepts, such as “testosterone is the baseball and the receptor is the glove.” Fourth, they used second-person narration to describe patients’ potential experiences, such as “your brain’s okay but your body doesn’t want to get off the couch.” Finally, they used constructed dialogues, in which they spoke from patients’ perspectives, to illustrate potential experiences or choices during a trial. For example, voluntary participation was explained through a hypothetical scenario where the patient might say, “This doesn’t make sense. I’m not ready.” This study identified plain language strategies that may help patients understand information about cancer clinical trials. These strategies hold promise as part of a shared decision-making process in the context of cancer clinical trials.