Ultrafiltration (UF) has evolved into a pivotal technique for managing fluid volume and mitigating inflammatory responses during cardiac surgery involving cardiopulmonary bypass (CPB). Initially aimed at volume management, UF has expanded its utility to remove inflammatory mediators, which are introduced by CPB and contribute to clinical manifestations. Various UF techniques, including conventional (CUF), modified (MUF), and zero-balance ultrafiltration (Z-BUF), can be applied at different stages of CPB. While each technique offers unique benefits, they commonly contribute to hemoconcentration, reduced blood product requirements, and mitigation of systemic inflammatory response syndrome (SIRS). This chapter will discuss the different types of ultrafiltration, ultrafiltration circuitries, application methodologies, and their clinical impacts, providing a thorough understanding of their utilization and benefits in cardiac surgery involving CPB.