Purpose. Evaluation of the communication and informed consent process in phase I clinical trial interviews to provide authentic, practice-based content for inclusion in a communication skills training intervention for health care professionals. Patients and Methods Seventeen oncologists and 52 patients from five United Kingdom cancer centers consented to recording of phase I trial discussions. Following each consultation, clinicians completed questionnaires indicating areas they felt they had discussed, and researchers conducted semistructured interviews with patients examining their recall and understanding. Patients and oncologists also completed the Life Orientation Test-Revised questionnaire, measuring predisposition toward optimism. Independent researchers coded the consultations identifying discussion of key information areas and how well this was done. Observed levels of agreement were analyzed for each consultation between oncologist-coder, oncologist-patient, and patient-coder pairs. Results In several key areas, information was either missing or had been explained but was interpreted incorrectly by patients. Discussion of prognosis was a frequent omission, with patients and coders significantly more likely to agree that oncologists had not discussed it (odds, 4.8; P < .001). In contrast, coders and oncologists were more likely to agree that alternate care plans to phase I trial entry had been explained (odds, 2.5; P = .023). Conclusion These data indicate that fundamental components of communication and information sharing about phase I trial participation are often missing from interviews. Important omissions included discussion of prognosis and ensuring patient understanding about supportive care. These findings will inform educational initiatives to assist communication about phase I trials.