Composite tissue allotransplantations would contribute to the reconstructions of the congenital, traumatic and tumors deformities. PURPOSE--The aim of this study is to prevent or inhibit the rejection in limb vascularized allotransplantation; decrease the toxicity of available immunosuppressive agents; determine whether combination subtherapeutic doses of CsA +RS-61443 will have an additive immunosuppressive effect. METHODS--Five groups were studied, using Brown-Norway limb donors and Fischer 344 recipient rats: group A Untreated autograft controls; group B Untreated allograft controls; group C Allografts: CsA 1.5 mg/kg/d SQ; group D Allograft: RS-61443 15 mg/kg/d; group E Allograft: combination CsA + RS-61443. RESULTS--The results were the following concerning the rejection: Group A animals displayed no rejection clinically (0%). All the skin biopsies obtained were devoid of rejection (grade 0). Group B animal developed rejection at 10-13 days post-transplantation. Skin biopsies confirmed the epidermal necrosis (grade 4). Group C animals developed rejection in 55%. Group D animals developed rejection in 94%. In contrast, Group E animals had 96% rejection-free survival up to POD 172 thus far. CONCLUSION--Combination subtherapeutic doses of CsA + RS-61443 was effective in preventing acute rejection of limb allografts and had an additive immunosuppressive effect because of the agents immunosuppressive synergistic effect.