Renal and electrolyte abnormalities occur more frequently in the elderly. Renal failure is often present in this population but is poorly recognizable if serum creatinine determinations alone are utilized to assess renal function. In general, electrolyte disturbances are compounded in their intensity of presentation by the sluggish capacity for excretion of electrolyte, water, or drug loads inherent to the aging process. In addition, the presence of senescence-related organ system deterioration amplifies observed effects. Electrolyte replacement therapies are best applied in a two-pronged fashion which involves bringing the patient out of immediate danger and then more gradually restoring abnormal parameters towards normal.