It can be assumed that patients' participation in a phase I study will have an important impact on their partners' life. However, evaluation of partners' experiences while patients are undergoing experimental treatment and of their well-being after the patient's death is lacking. We aimed to explore partners' experience of patients' participation in phase I studies and to investigate their well-being after a patient's death.

This was an observational study conducted after the patient's death. Partners of deceased patients who had participated in a phase I study completed a questionnaire designed by us for experience evaluation and the Beck Depression Inventory for Primary Care, the Hospital Anxiety and Depression Scale, the Inventory of Traumatic Grief, and the RAND-36 Health Survey.

The median age of the 58 participating partners was 58 years (range: 51–65), and 67% was female. Partners reported negative effects on patients' quality of life, but only 5% of partners regretted patients' participation. Approximately two years after the patients' death, 19% of partners scored for depression, 36% for psychological distress, and 46% for complicated grief, and partners generally scored significantly lower on social and mental functioning compared to normative comparators.

Although partners reported negative consequences on patients' quality of life, most did not regret patients' participation in the phase I studies. Prevalence of depression, psychological distress, and complicated grief seemed important problems after a patient's death, and these must be considered when shaping further support for partners of patients participating in phase I trials.