This study was conducted to assess the health risk of carcinogenic heavy metals such as arsenic, nickel, chromium and cadmium Ambient concentrations of these metals were measured bimonthly, during May 1987 to March 1988. Respirable Particle concentrations of As, Ni, Cr, Cd in traffic area(Shinchon) were 16ng/㎥, 43ng/㎥, 4.2ng/㎥, 6.6ng/㎥, respectively, and in residential area(Bulkwang) were 25ng/㎥, 32ng/㎥, 4.7ng/㎥, 8.9ng/㎥, respectively. Carcinogenic risk of each metal was calculated by multiplication of ambient concentration and unit risk of the metal which was referred to recent version of Integrated Risk Information System(IRIS). Sum of the risk from these for metals was 9.8$ imes$10$^{-5}$ as individual risk in traffic area and 13.9$ imes$10$^{-5}$ in residential area.