Non-compliance with hemodialysis treatments--defined as missing more than 1 treatment over the 3 month period prior to the study

Unable to verbally communicate in English or Spanish

Current requirement for hemodialysis more than three times per week due to medical comorbidity (including fourth session for ultrafiltration)

Currently on daily or nocturnal hemodialysis, or less than 3 months since discontinued such treatment

Expected geographic unavailability at dialysis center during any phase of the trial

Less than 3 months since the patient returned after acute rejection resulting in allograft failure

Currently in acute care or chronic care hospital

Pregnancy

Current involvement in any non-observational trial

Unable or unwilling to follow the study protocol for any reason (including mental incompetence)

Unable or unwilling to provide informed consent or sign IRB-approved consent form

Pace maker, implantable pump, artificial joint

Amputation of a limb

Comparison Study of Daily Ultrafiltration and Twice-weekly Hemodialysis