Study design: An in vivo study in Wistar albino rats with injured spinal cord. Setting Department of Neurosurgery, Biochemistry and Pathology, Gazi University, Ankara, Turkey. Objectives: The aim of this study was to investigate and compare the effects of FK506 an immunosupressive agent with methylprednisolone (MP) on lipid peroxidation (LP) in injured spinal cord tissue. Method: A total of 28 adult healthy Wistar albino rats were subjected to traumatic spinal cord injuries (SCI) by using an aneurysmal clip compression technique, and they were divided into four groups. The G1 group (n = 8) received FK506 (1 mg/kg); the G2 group (n = 8) received FK506 (1 mg/kg) and MP (30 mg/kg); the G3 group (n = 6) received only MP (30 mg/kg): and the G4 group (n = 6) received no medication. The injured spinal cord tissue was studied by means of lipid peroxides, malondialdehyde (MDA), with thiobarbituric acid reaction and additionally the FK506 (G1); the MP (G3) groups were studied for histopathologic alterations 72 h after SCI with eight separate animals. Results: Although LP values of G1, G2, G3 showed no statistical difference between intergroup analyses (P = 0.547), a histopathological examination revealed that in the group that received MP, the oedema pattern was more significant than the group that received FK 506. Another interesting finding was the presence of polymorphonuclear leucocytes in the MP group, whereas no infiltration was found in the FK506 group. Conclusion: Analysis of the results indicated that FK506 is a valuable pharmacological agent that could be used to decrease the LP and polymorphonuclear leucocyte infiltration and inflamatory reactions in the injured spinal cord tissue.