The contents of Pb and Cd in two species of Iranian tuna fish (yellowfin and skipjack), which were caught from the Persian Gulf and Oman Sea, and the effects of canning processing steps on their contents were assessed by electrothermal atomic absorption spectrometry. The results revealed that the levels of lead and cadmium throughout the processing steps in yellowfin were in range of 0.154±0.019–0.441±0.025μg/g and 0.029±0.002–0.084±0.0005μg/g, respectively. Pb and Cd concentrations from received fish to final product in skipjack were found to be in range of 0.072±0.031–0.218±0.031μg/g and 0.016±0.001–0.062±0.002μg/g, respectively. The limit of detection for lead and cadmium were 0.058μg/g (11.6022μg/l) and 0.0007μg/g (0.1485μg/l), respectively. Results from paired sample t-test analysis showed that defrosting, cooking, and sterilisation by autoclave would reduce the contents of lead and cadmium, considerably.