Purpose: The healthcare sector is responsible for 6–7% of CO₂ emissions. The intensive care unit (ICU) contributes to these CO₂ emissions and a shift from a linear system to a circular system is needed. The aim of our research was to perform a material flow analysis (MFA) in an academic ICU. Secondary aims were to obtain information and numbers on mass, carbon footprint, agricultural land occupation and water usage and to determine so-called “environmental hotspots” in the ICU. Methods: A material flow analysis was performed over the year 2019, followed by an environmental footprint analysis of materials and environmental hotspot identification. Results: 2839 patients were admitted to our ICU in 2019. The average length of stay was 4.6 days. Our MFA showed a material mass inflow of 247,000 kg in 2019 for intensive care, of which 50,000 kg is incinerated as (hazardous) hospital waste. The environmental impact per patient resulted in 17 kg of mass, 12 kg CO₂ eq, 300 L of water usage and 4 m² of agricultural land occupation per day. Five hotspots were identified: non-sterile gloves, isolation gowns, bed liners, surgical masks and syringes (including packaging). Conclusion: This is the first material flow analysis that identified environmental risks and its magnitude in the intensive care unit.