Background The aim of the current study was to investigate the role of interleukin (IL)-2, interferon (IFN)-γ, IL-4 and IL-10 in a concordant hamster-to-rat cardiac xenotransplantation model. Methods A hamster-to-rat cardiac transplantation was performed using SD rats as recipients of Golden Syrian hamster hearts. A total of 60 SD rats were divided into four groups and treated as follows: control group (n=15); splenectomy group (n=15); CsA group (n=15); CsA + splenectomy group (n=15). Levels of IL-2, IFN-γ, IL-4 and IL-10 were measured by enzyme linked immunosorbent assay (ELISA). Sera were harvested at different time points in each group: day 1, and 3 as well as the day the xenograft stopped beating in the control group and CsA group; day 1, 3, 7, 14 and 30 in the splenectomy group and CsA+splenectomy group. The expression of P-selectin and intercellular adhesion molecule-1 (ICAM-1) was examined by immunohistochemical analysis of the xenograft after cardiac xenotransplantation. Results Serum levels of IL-2 and IFN-γ were upregulated in untreated (day 3) and splenectomy-treated animals (day 7) compared to CsA + splenectomy treated animals (day 7). IL-10 was upregulated in long-term survival recipients following splenectomy + CsA. Neither P-selectin nor ICAM-1 expression was detected in long-term survival xenografts. Conclusions Serum IL-2 and IFN-γ were elevated following acute vascular rejection. Serum IL-10 was correlated to immunosuppression and protective effects in long-term survival rats following concordant cardiac xenotransplantation.