The aim of this study is to determine the protective effect of L-carnitine (LCAR) against the toxicity of doxorubicin (DOX) an antineoplastic drug, treatment dose on plasma sialic acid (SA), malondialdehyde (MIDA) and blood reducte glutathion (GSH) levels. In this study 21 healthy New Zealand rabbits were used. The rabbits in Group I (n=8) 0.6 mg/kg DOX, in Group 11 (n=7) 0.6 mg/kg DOX with 1000 mg/kg LCAR, in Group III (n=6) 1000 mg/kg dose were administered intra peritoneally along 6 days. In all groups the control groups were appreciated before administration. The blood samples were obtained after 2 h from administration. SA levels in Group I and in Group 11 significantly increased (P<0.001) during application than before administration, but SA levels in Group III decreased (P<0.001). GSH level in Group 1 decreased (P<0.05) from third day comparing to first day. GSH levels in Group III significantly increased (P<0.05) from second day of administration. MDA levels on 3, 4, 5 and 6th days of Group I incresead (P<0.001) when compared to first and second days and control group and GSH level increased (P<0.01) in Group II. MDA levels in Group III decreased (P<0.05) in all days. TSA and LBSA levels in Group I increased (P<0.001) comparing to Group 11 on 2, 3, 4, 5 and 6th days of administration. GSH levels in Group 111 increased on 2 and 3rd days (P<0.01) and increased on 4, 5 and 6th days (P<0.001) comparing to Group I and Group II. MDA levels in Group I increased on 1, 2, 4, 5 and 6th days (P<0.001), on 3rd days (P<0.01) comparing to Group II. In conclusion, it may be suggested that L-carnitine administration could have a protective effect during doxorubisin administration through alteration plasma SA, MDA and blood GSH levels.