A concerted effort to test the hypothesis that TDM will improve outcome in mycophenolate mofetil therapy in a prospective randomised trial is to be made if we want to have a solid base for the continued measurements of mycophenolic acid concentrations in the future. This trial aims to demonstrate the added value of TDM for mycophenolic acid, by comparing fixed dose treatment with concentration controlled mycophenolate mofetil treatment in kidney transplant recipients.