Purpose The number of patients with cancer enrolling in phase I trials is expected to increase as these trials incorporate patient selection and exhibit greater efficacy in the era of targeted therapies. Despite the fact that people with advanced cancer often require a caregiver, little is known about the experience of caregivers of people enrolling in oncology phase I clinical trials. We conducted a cross-sectional study assessing the distress and emotion regulation of caregivers of phase I trial participants to inform the design of future interventions targeting the unique needs of this population. Methods Caregivers of oncology patients were approached at the patient's phase I clinical trial screening visit. Caregiver participants completed a one-time survey incorporating validated instruments to comprehensively assess distress and emotion regulation. Basic demographic information about both the caregiver and patient was collected. Results Caregivers exhibited greater distress than population norms. Emotion regulation was also moderately impaired. Respondents identified positive aspects of caregiving despite exhibiting moderate distress. Conclusion Enrollment of a patient in a phase I clinical trial is a time of stress for their caregivers. This pilot study demonstrates the feasibility of engaging caregivers of phase I trial participants and the need to better support them through this component of their caregiving experience. © 2014 Springer-Verlag Berlin Heidelberg.