BACKGROUND: Emergency department (ED) crowding causes increased mortality. Professionals working in crowded departments feel unable to provide high-quality care and are predisposed to burnout. Awareness of the impact on patients, however, is limited to metrics and surveys rather than understanding perspectives. This project investigated patients' experiences and identified mitigating interventions. METHODS: A qualitative service evaluation was undertaken in a large UK ED. Adults were recruited during periods of high occupancy or delayed transfers. Semi-structured interviews explored experience during these attendances. Participants shared potential mitigating interventions. Analysis was based on the interpretative phenomenological approach. Verbatim transcripts were read, checked for accuracy, re-read and discussed during interviewer debriefing. Reflections about positionality informed the interpretative process. RESULTS: Seven patients and three accompanying partners participated. They were aged 24-87 with characteristics representing the catchment population. Participants' experiences were characterised by 'loss of autonomy', 'unmet expectations' and 'vulnerability'. Potential mitigating interventions centred around information provision and better identification of existing ED facilities for personal needs. CONCLUSION: Participants attending a crowded ED experienced uncertainty, helplessness and discomfort. Recommendations included process and environmental orientation.