A prospective randomized trial was carried out to compare the long-term effects of triple therapy based on low-dose cyclosporin A (CyA), low-dose methylprednisolone (MP) and azathioprine (Aza) with three different double drug immunosuppressive regimens. After initial triple drug immunosuppression for 10 weeks, 128 patients were randomized into four different immunosuppressive groups: one group continued with triple therapy (group A) and the three other groups were treated with different combinations of two drugs: Aza and CyA (group B), Aza and MP (group C) and CyA and MP (group D). This report presents the 2-year results. For groups A, B, C and D, graft survivals were 75%, 78%, 84% and 81%, respectively, and patient survivals were 84%, 84%, 84% and 94%, respectively. After 2 years no patient had returned to dialysis in group C compared with one to three patients in every CyA-using group. However, at the end of the 2nd year, group C included more patients with deteriorating graft function than the other groups. Median serum creatinine was 107, 120, 139 and 129 mumol/l for groups A, B, C and D, respectively. For the patients who remained on the original randomized protocol, there were no significant differences in graft function tests between the four groups, the median creatinine being 115, 115, 118 and 113 mumol/l for groups A, B, C and D, respectively. Thus, no graft deterioration had occurred during the 2 years for these patients following the original protocol.(ABSTRACT TRUNCATED AT 250 WORDS)