In the paper, the effects of differences in land use of a catchment and settlements on the variability of heavy metals concentrations (Zn, Pb, Cu, Cd, Ni) in the Narew River and some of its tributaries such as the Biebrza, upper Narew, Pisa, Omulew and Rozoga rivers were studied. The investigations continued from 1997 to 2002. The areas dewatered by the watercources differ considerably in terms of environmental features (forests, wetlands, bogs and water reservoirs), land use (arable lands, grasslands) and population (man-made areas). The total catchment of the Narew River at the cross-section in Zamski Kościelne was also taken into account. The urban areas make up from 0.5% of the Rozoga River to 2.5% of the upper Narew catchment. Water samples were collected quarterly (April, July, October and January) from four study sites located near the river mouth and were analyzed for Zn, Pb, Cu, Cd and Ni by the AAS method. The results showed that concentrations of Pb, Cu, Cd and Ni increased along the Narew River due to the accumulation of the elements in water. A significant influence on high heavy metal concentrations in water was produced by the town of Białystok, a source of large amounts of municipal pollutants discharged into the river. This mainly affected the content of Zn, as the highest pollution with this element was detected in the upper Narew River. The lowest Zn concentrations were observed in the Omulew River water, where forests dominated in the area, covering more than 48% of the catchment. The research showed that wetlands and lakes significantly decreased Pb, Cu, Cd and Ni concentrations in flowing water, but the presence of large inhabited areas with dense population and municipal pollution increased concentrations of heavy metals in river water.