Many transplant teams are reluctant to accept kidneys preserved with intracellular electrolyte flushing followed by simple cold storage when preservation time exceeds 24 hr. This study from one center is a comparison of 63 primary cadaver kidney grafts preserved with Collins 2 solution flush followed by cold storage for 9 to 23 1/2 hr to 42 primary cadaver kidney grafts preserved by the same method for 24 to 44 1/2 hr. Kidneys cold-stored for over 24 hr had a significantly increased requirement for dialysis in the first week following transplantation (55% versus 30%). One-month serum creatinine nadirs and actuarial graft survivals were not significantly different. Cadaver donor methylprednisolone (30 to 60 mg/kg) 2 to 9 hr prior to kidney removal reduced the requirement for first-week hemodialysis in the kidneys cold-stored for over 24 hr (23% versus 69%, P under 0.05). A human kidney preserved by the same method and cold-stored for 61 hr was successfully transplanted into a 38-year-old myelodysplastic. Satisfactory human kidney preservation can occur with intracellular electrolyte flush solutions followed by cold storage for over 24 hr when the warm ischemia time is very short.