Neoral is a new formulation of cyclosporine based on microemulsion technology, designed to provide increased and more reliable absorption of the medication. The aim of this study was to assess whether conversion from Sandimmune to Neoral provides safe and effective oral immunosuppression in stable liver transplant recipients. We studied 59 stable liver transplant recipients (being treated with prednisone, azathioprine, and Sandimmune). All patients were enrolled in an open-label study in which they were converted from Sandimmune to Neoral therapy at a dose ratio of 1:1. Thirty-nine patients underwent duct-to-duct bile duct anastomoses, and 20 underwent Roux-en-Y bile duct anastomoses. After conversion, the Neoral dosage was adjusted on the basis of trough levels measured at weeks 1, 2, 3, 4, 6, 8, and 12. To assess safety and tolerability, we prospectively obtained serial information, including laboratory data and information on side effects. Standard statistical methodology was used. A total of 59 patients (23 men, 36 women; mean age, 55 years; mean follow-up after liver transplantation, 5.7 years) completed 3 months of follow-up after conversion from Sandimmune to Neoral. There were 32 dosage changes; 22 (69%) required reduction of the Neoral dose. Mean cyclosporine trough levels remained above 100 ng/mL during the follow-up period. There were no significant differences between cyclosporine levels in patients with duct-to-duct or Roux-en-Y bile duct anastomoses. There were no episodes of rejection during the 3-month follow-up period. The side effect profile was similar in both groups, except for a significant reduction in the number of patients with headaches after Neoral conversion. Liver transplant recipients can safely be converted from Sandimmune to Neoral. Neoral was well tolerated in this population.