BACKGROUND: Little is known concerning gastric motility after renal transplantation and on the impact of immunosuppressants on gastric emptying. METHODS: Gastric emptying was measured in renal transplant recipients, taking different immunosuppressive therapy (steroids and cyclosporine/azathioprine/FK-506), and compared with normal volunteers. RESULTS: After renal transplantation, gastric emptying of liquids was normal, irrespective of the type of immunosuppression. However, solid gastric emptying was significantly faster in FK-506-treated patients compared with patients taking cyclosporine for all measured emptying parameters. Compared with normal volunteers solid gastric emptying was slower in patients taking cyclosporine, comparable in azathioprine treated patients, and characterized by an unusual short lag phase in patients taking FK-506. CONCLUSIONS: In stable renal transplant recipients gastric emptying of solids was significantly faster in patients on FK-506 compared with patients taking cyclosporine. Therefore, FK-506 may be the immunosuppressant of choice after solid organ transplantation in patients with problems related to gastroparesis.