This is a prospective cohort study in renal transplant patients who fasted or who did not fast for three consecutive Ramadans. The baseline estimated glomerular filtration rate (GFR), mean arterial pressure (MAP), and urinary protein excretion before the first Ramadan were compared to those after the third Ramadan in 35 fasters and 33 nonfasters. The effect of age, time after transplantation, presence of diabetes mellitus (DM), and proteinuria on changes in the GFR were studied. The two groups were comparable in gender, age, donor source, time posttransplantation, presence of DM, hypertension, proteinuria, serum creatinine, and MAP. Among the fasters, there was no change in estimated GFR after fasting for three Ramadans (56.4 mL/min versus 55.4 mL/min, P=0.8) even after adjusting for age, DM, baseline GFR, proteinuria, or time after transplantation. There were no significant differences between the fasters and the nonfasters in the changes in GFR, MAP, and urinary protein excretion between baseline and the third Ramadan.