The concentration of heavy metals in marine fishes has received much interest in recent years. Heavy metal contamination may arise from urban and industrial wastes as well as from agricultural and natural sources. Many of these trace heavy metals are important in the maintenance of normal physiological function of the body. While others are well known tobe toxic to the ecosystem as a whole and fo man in particular. Considerab•e interest has been focused on arsenic due to ifs high toxicity. This interest has been directed towards the commercial and sports fishes since high levels of arsenic in these species represent a potential human health hazard. Within the past 10 years, the use of marine fishes of Iran as a source of food was highly increased by iranians and people of other countries. In the present investigation, the arsenic concentration in two commercial canned fishes of Iran, tuna fish and sardine, was determined to find the degree of their contamination with arsenic and to control human health hazards. Besides, the results were compared with previous reports.