Intravenous administration of cyclosporine (Sandimmune) to rapidly and effectively achieve therapeutic serum levels in transplant recipients has been the treatment standard in many transplantation centers. With the development of microemulsion cyclosporine (Neoral), that standard is changing. Neoral has greater bioavailability than the oral form of Sandimmune and, consequently, can be more efficacious and cost-effective. To test this hypothesis, we undertook a retrospective study of Sandimmune and Neoral in the treatment of 66 children who underwent uncomplicated orthotopic liver transplantation in the Texas Medical Center between April 1991 and December 1997. Both forms of cyclosporine were evaluated in terms of in-patient treatment cost, recuperative time in the intensive care unit and duration of hospitalization. Twenty-two patients were treated orally with Neoral, and 44 patients were treated intravenously with Sandimmune for a mean time of 14 d. Once the blood concentration of Sandimmune reached a steady state, as confirmed by daily measurements of the trough level, the patients in the Sandimmune group were converted to oral cyclosporine. None of the 22 patients treated with Neoral required intravenous treatment. The mean time spent in the intensive care unit was 4 d for the Neoral group and 5.5 d for the Sandimmune group. The mean duration of hospitalization from the date of transplantation to discharge was 12 d for the Neoral group and 20 d for the Sandimmune group (p < 0.001). Based on these results, we determined that the overall cost per patient in the Neoral group was $3598 less than that per patient in the Sandimmune group.