This chapter discusses about fluids and electrolytes, where most patients manifest a variety of fluid and electrolyte disorders that require attention. The immediate postoperative period is particularly complex as acute renal failure, abrupt changes in glomerular filtration rate. Hemodialysis can effectively raise plasma sodium levels but the rapid rate of correction may have adverse consequences. Hyperkalemia is the most frequent electrolyte disorder in these patients requiring preoperative hemodialysis. Most practitioners avoid hemodialysis on the day of transplant surgery to decrease complications relating to volume depletion and hypokalemia. Hypercalcemia associated with hyperparathyroidism is controlled increasingly with calcimetic therapy. Management in the early postoperative period is done conservatively with volume restriction, preload reduction and supplemental oxygen. Hyponatremia in association with hyperkalemia and a rising creatinine in the immediate postoperative period may be a sign of an obstructive uropathy and urinary leak and should be investigated with an imaging study.