In addition to gastrointestinal tract symptoms such as nausea, vomiting, and loss of appetite, impaired gastric emptying time (GET) may be related to nutritional parameters and nutritional status of patients on renal replacement therapy (RRT). Patients on RRT are affected by several factors such as uremic toxins, the presence of dialysate in the peritoneal cavity, and the drugs used against renal allograft rejection. In this study, we investigated the gastric emptying time and its relationship with biochemical and nutritional parameters in patients on RRT: those on hemodialysis and peritoneal dialysis, and renal transplantation patients. Seventy-five patients, 44 on hemodialysis, 16 on peritoneal dialysis, and 15 renal transplant patients, were included in the study. They were examined for gastric emptying time using a radioisotopic method. The results were compared with the GET of healthy subjects. Each group of patients was evaluated in terms of hemoglobin, hematocrit, blood urea nitrogen (BUN), creatinine, blood glucose, total protein, albumin, serum lipids, parathyroid hormone (PTH) and body mass index and biceps and triceps skinfold. The mean GET of patients on RRT was significantly longer than the mean GET of healthy subjects (87.8 +/- 23.4 vs. 55 +/- 18 min, p<0.05). The mean GET of each therapy subgroups was significantly longer than the healthy subjects (the mean GET was 85.1 +/- 22.4 min for hemodialysis, 87.7 +/- 31.8 min for peritoneal dialysis, and 94.6 +/- 16.7 min for renal transplant patients, respectively, p<0.05). On the other hand, the differences in the mean GET between the three therapy subgroups were not statistically significant (p>0.05). In addition, time on replacement therapy inversely and blood glucose positively correlated with GET in renal transplant patients. In conclusion, GET was longer in patients on all three RRT modalities than in healthy subjects. GET was not significantly different in dialysis patients and renal transplant patients.