Tacrolimus extended-release (XL) is a once-daily formulation recently developed to reduce the frequency of dosing for patients currently using the twice-a-day formulation of tacrolimus (TAC). As reported previously, 67 kidney transplant recipients were safely converted (1:1 mg basis, total daily dose) from TAC twice-a-day to XL once-daily in the morning and were maintained on an am dosing regimen of XL using the same therapeutic monitoring and patient care techniques currently employed with TAC. The 2-year postconversion patient (100%) and graft (98.5%) survival, incidence of biopsy-confirmed acute rejection (6.0%), incidence of multiple rejections (1.5%), and safety profile (posttransplant diabetes, hyperlipidemia, hypertension, infections, renal dysfunction, hepatic dysfunction, and malignancies) were consistent with or more favorable than those previously reported for TAC twice-a-day.