Brazil’s Unified Health System (in portuguese, Sistema Único de Saúde – SUS) represents one of the largest universal public health systems in the world, grounded in the principles of universality, equity, and comprehensiveness. This article explores a counterfactual yet analytically relevant question: what would be the social, sanitary, and professional consequences if SUS were dismantled or ceased to exist? Through a critical public health and political economy perspective, the essay examines the structural role of SUS in reducing inequalities, guaranteeing access to care, and sustaining health workforces across the country. The analysis highlights the likely amplification of health inequities, the fragmentation of care, and the collapse of preventive and community-based actions in a scenario of system extinction. Particular attention is given to the assistential dimension, discussing the impacts on medical practice, dentistry, social work, and biomedicine. The article argues that the absence of SUS would not merely represent an institutional change but a profound social regression, reshaping health as a market commodity and deepening historical injustices. Ultimately, the text reinforces SUS as a civilizational achievement whose erosion would compromise population health, professional ethics, and democratic governance.