There being an increasing number of patients with functioning renal allograft, more long-term complications are expected. To our knowledge, few studies have been published to date regarding the Intensive Care Unit (ICU) re-hospitalization after kidney transplantation. The purpose of this study was to compare re-hospitalization of kidney transplant recipients in ICU and that in other wards. This study was a retrospective comparative analysis of 581 consecutive re-hospitalizations of kidney recipients in Baqyiatallah Hospital from 1994 to 2006. A total of 581 re-hospitalizations were divided into admissions in ICU and admissions in other wards. The two groups were compared in terms of demographic variables, length of stay at hospital, causes of end-stage renal disease (ESRD), time intervals between transplantation and re-hospitalization, hospitalization costs, and mortality rates. 25 patients (4%) used ICU care in their re-hospitalizations. Causes of ICU admissions were renal dysfunction in 36%, CVA in 24%, sepsis in 16%, brain tumor in 8%, brain abscess in 4%, diabetic ketoacidosis in 4%, trauma in 4% and hemodynamic shock in 4%. We found a significant higher mean (SD) age (49.4 ±11.3 vs 39.9 ±14.1, p=0.001), length of stay at hospital (18.36±22.88 vs 10.30 ±8.74, p=0.00), mortality rate (32% vs 2.8%, p=0.00), and mean (SD) hospitalization costs (9,075 ±9,945 vs 2,725 ±3,183, p=0.00) (1000 IRR) in the ICU admissions than those in others. There was no significant difference in sex, ESRD cause, and TH-time between the two groups (p>0.05). ICU re-admission imposes higher costs and prolonged length of hospital stay upon the health care system (an approximate increase of 250% and 80%, respectively). Renal dysfunctions, sepsis, and cerebrovascular accidents seem to be the principal causes of ICU readmission after renal transplantation.