Background An ageing population in the EU leads to a higher need of long-term institutional care at the end of life. At the same time, healthcare costs rise while resources remain limited. Consequently, an urgency to extend our knowledge on factors affecting efficiency of long-term care facilities (LTCFs) arises. This study aims to investigate and explain variation in technical efficiency of end-of-life care within and between LTCFs of six EU countries: Belgium (Flanders), England, Finland, Italy, the Netherlands and Poland. In this study, technical efficiency reflects the LTCFs' ability to obtain maximal quality of life (QoL) and quality of dying (QoD) for residents from a given set of resource inputs (personnel and capacity). Methods Cross-sectional data were collected by means of questionnaires on deceased residents identified by LTCFs over a three-month period. An output-oriented data-envelopment analysis (DEA) was performed, producing efficiency scores, incorporating personnel and capacity as input and QoL and QoD as output. Scenario analysis was conducted. Regression analysis was performed on explanatory (country, LTCF type, ownership, availability of palliative care and opioids) and case mix (disease severity) variables. Results 133 LTCFs of only one type (onsite nurses and offsite GPs) were considered in order to reduce heterogeneity. Variation in LTCF efficiency was found across as well as within countries. This variation was not explained by country, ownership, availability of palliative care or opioids. However, in the 'hands-on care at the bedside' scenario, i.e. only taking into account nursing and care assistants as input, Poland (p = 0.00) and Finland (p = 0.04) seemed to be most efficient. Conclusions Efficiency of LTCFs differed extensively across as well as within countries, indicating room for considerable efficiency improvement. Our findings should be interpreted cautiously, as comprehensive comparative EU-wide research is challenging as it is influenced by many factors.