Open partial nephrectomy (PN) is a challenging operation that requires complete tumor resection with a negative margin, maximal protection from ischemic injury, and preservation of functioning renal parenchyma; with the aim of maximizing cancer-specific survival and minimizing postoperative chronic kidney disease, morbidity, and mortality. This chapter provides a detailed discussion of the rationale for PN as well as its current indications. The importance of minimizing renal ischemia and other predictors of postoperative CKD is discussed. The techniques of open PN are described.