The relationship between size (length and weight) and metal concentrations in different tissues of two commercially valuable fish species (Hilsa shad, Tenualosa ilisha and tiger tooth croaker, Otolithes ruber) from the north of Persian Gulf were evaluated. Concentrations of the metals in fish species ranged as follows: Cd 0.08-1.34; Pb 0.67-4.43; Cu 3.07-23.38; Co 0.64-5.03; Ni 2.15-7.69 μg/g dry weight, respectively. Metal content in both fish varied with type of metals and tissues. Results showed significant positive relationships between metals and fish size in T. ilisha, while those in O. ruber were not significant in most cases.