Adequacy of hemodialysis is frequently equated with Kt/V(urea) , the amount of urea clearance (K) multiplied by time (t) and divided by urea distribution volume (V). Several formulas have been developed to calculate Kt/V(urea) from the pre- and post-dialysis urea concentrations. In three-times-weekly hemodialysis, a single pool (spKt/V(urea)) value of 1.3 per treatment is commonly considered to indicate adequate therapy. Despite providing the recommended spKt/V(urea) of 1.3 per treatment, short dialysis with rapid ultrafiltration is associated with multiple intradialytic and interdialytic complications. Patients experience cramps, nausea, vomiting, headaches, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. According to Webster's dictionary, "optimal" means most desirable or satisfactory; "adequate" means sufficient for a specific requirement or barely sufficient or satisfactory. Optimal dialysis is the method of dialysis yielding results that cannot be further improved. New approaches, including hemeral quotidian or long nocturnal dialysis, provide opportunities to abandon the notion that adequate dialysis is "good enough" for our patients. Optimal dialysis should be our goal. Dialysis sessions should be long and frequent enough to provide excellent intra- and interdialytic tolerance of hemodialysis, normalization of serum calcium and phosphorus, blood pressure control, normal myocardial morphology and function, and hormonal balance, and to eliminate all, even subtle, uremic symptoms.