Context End-of-life palliative care aims to provide comprehensive care and can be marked by somatic, psychosocial, and spiritual distresses, requiring interdisciplinary care. However, interdisciplinary care is costly, and palliative care services, similar to all other medical services, are pressurized to be as cost-effective as possible. Objectives To describe the case complexity of palliative care inpatients, we evaluated possible correlations between complexity and the provision of care and identified complexity subgroups. Methods Patients (N = 222) hospitalized in a specialist palliative care unit in Switzerland were assessed for biopsychosocial complexity using INTERMED. Based on a chart review, INTERMED scores were determined at admission and at the end of hospitalization or at death. Descriptive statistics and Pearson’s correlation coefficients were used to estimate the association between biopsychosocial complexity and the amount and type of care provided. Principal component analysis (PCA) was conducted to explain variance and identify patient subgroups. Results Almost all patients (98.7%) qualified as complex, as indicated by INTERMED. Provision of care was positively correlated (r = 0.23, p = 0.0008) with INTERMED scores upon admission. The change in the INTERMED score during the stay correlated negatively with the provision of care (r = −0.27, p = 0.0001). PCA performed with two factors explained 49% of the total variance and identified two subgroups that differed in the INTERMED psychosocial-item scores. Conclusion Inpatients receiving specialist palliative care showed the highest complexity score of all populations assessed to date using INTERMED. Correlations between biopsychosocial complexity and care provided, and between care and decrease in complexity scores can be considered indicators of care efficiency. Patient subgroups with specific requirements (psychosocial burden) suggested that palliative care teams require specialist palliative care collaborators. Key message Palliative care provision correlates with case complexity and is effective.