A column packed with Amberlite XAD-16 resin was used for preconcentration and determination of chemical forms of heavy metals such as Cr, Ni, Cu, Cd and Pb in lake water samples. The concentrations of the metals bound to humic substances and of free metal ions were determined after their sorption-elution on the resin. The method optimized with sodium tetraborate reagent was used in determining the free metal ions. Both flame- and graphite furnace-atomic absorption spectrometry was used to determine the metals in lake water samples. Recoveries were quantitative for all the elements studied (greater than or equal to 95%). The detection limits (DL, mug mL(-1)) were 0.007 for Cu; 0.002 for Cd; 0.022 for Pb; 0.038 for Cr; 0.008 for Co; 0.015 for Mn; and 0.054 for Ni (n=20, 3s). The precision values for the same elements were in the range of 1.3 to 2.4% (n=10).