This study was aimed at evaluating brain, liver and kidney tissue NO and malondialdehyde (MDA) after long term administration of L-arginine a nitric oxide donor and N nitro-L-arginine methyl ester (L-NAME) a NO inhibitor. Three groups were established; control group received 0.5 ml isotonic NaCl, L-arginine group was given 200 mg/kg L-arginine and L-NAME group received 100 mg/kg L-NAME by intraperitoneal injection daily for 11 days. Rabbits were euthanized at the end of the experiment and brain, liver and kidney tissue samples were collected. Tissue NO and MDA levels were colorimetrically determined. There was no statistically significant difference in liver and kidney NO and MDA level between the groups while L-arginine administered group had higher brain NO and MDA levels when compared to other groups (P<0.05). As a result, long term administration of L-arginine increased brain tissue NO and MDA when compared to liver and kidney values.