Cyanide is a very toxic agent and is a major environmental pollutant. Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cell death. It is well known that the central nervous system and liver are the primary target organs in cyanide toxicity. The objectives of this study are: firestly to investigates the toxicity of potassium cyanide (KCN) on the liver and hippocampus of male rat, secondly to assess the ability of aqueous extract of celery and vitamin C in alleviation of the toxic effects on liver and hippocampus in cyanide-induced rats. Albino male rats (Sprague Dawley), weighing about 200ñ250 g were used in this study. Rats were randomly divided into four groups, 5 animals in each group, treated as following: Group I, (Normal Control): received normal diet and ad libtum water for 4 weeks. Group II, (Cyanide): received potassium cyanide at dose of 9.0 mg / k. b. wt. in drinking water for 4 weeks...