The average cost of cyclosporine over the first 6 months after renal transplantation has been $2450/recipient for recipients with stable renal function. Fifty-nine percent of all patients transplanted in 1984 do not have a third-party payment mechanism for outpatient medicines and many cannot afford cyclosporine. The expense of cyclosporine has, thus, mandated developing a protocol for conversion from cyclosporine to azathioprine. Using a protocol, which included a short overlap of cyclosporine and azathioprine and a temporary, modest increase in prednisone dose, 27 renal allograft recipients with stable renal function have undergone conversion of their immunosuppressive regimen approximately 6 months posttransplant with a minimum follow-up of 4 months from conversion. There has been no graft loss or patient death. Mean serum creatinine has been reduced in recipients with stable function after conversion (1.4 mg/dl 3 months postconversion compared to 1.8 mg/dl preconversion). However, acute breakthrough rejection has occurred in four recipients (15%), and, after reversal of rejection, mean serum creatinine is elevated (3.1 mg/dl) in this group. Only a single patient developed an infection during the conversion period. Thus, a policy of conversion from azathioprine appears to be a reasonable compromise for those patients who cannot afford long-term outpatient treatment with cyclosporine.