Concentrations of mercury in four freshwater fish species from Gandoman and Sooleghan Lagoons and Beheshtabad River were determined by cold vapor atomic absorption spectrometry. Concentrations of mercury in muscle of 90 fish ranged from 21 to 31 μg kg(-1) (mean = 26 μg kg(-1)). Statistical analysis showed no statistical relationship between mean mercury concentration and fish species, although concentration of mercury in different seasons and habitats was statistically different (p < 0.05). The results indicated that fish from Gandoman and Sooleghan Lagoons and Beheshtabad River have concentrations well below the maximum permissible levels of mercury according to international standards with no health risk for consumers.