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Dissolved heavy metal concentrations in Tadjan River water were determined through sampling and analysis of river water from 11 sampling stations along river including downstream of pollution sources during 2000-2001. Average concentrations of Cd, Cu, Mn, Ni, Pb, Zn, Co and Fe in winter were 9.7, 4.5, 28.5, 10.9, 20.3, 49.8, 23.1 and 391.5 µg/m3 respectively. In spring , summer and fall average metal concentrations were 12.1, 5.8, 35.0, 13.2, 24.9, 62.8, 27.9,465 and 80.3, 29.7, 74.5, 28.5, 58.5, 66.7, 22.1, 1767.7 and 62.5, 24.9, 62.1, 22.3, 41.3, 58.6, 22.9, 985.7 µg/m3 respectively. Concentrations of Cd, Ni and Pb particularly in summer and fall were higher than maximum acceptable concentrations and recommended concentrations of EPA and WHO. Results revealed that all dissolved metal concentrations except Co in summer are higher than other seasons. Effect of main pollution sources of the river (i.e. pulp and paper mill, city of Sari) on metal contamination of the river particularly in summertime and fall were determined.