Lake Orta (North Italy) is one of the series of north-south oriented lakes on the southern slopes of the Alps. Pollution of this lake began in the late 1920s with massive discharges of ammonium sulphate and copper from a rayon factory; phytoplankton, zooplankton and fish eventually disappeared. In the following decades, a low-pH regime was established due to the in-lake oxidation of ammonium to nitrate, the geological setting (granite, gneisses, and micaschists) favouring this development by not offering sufficient buffer capacity to the lake. Additional human activities in the catchment area, since the mid-seventies, have added further metals such as chromium, nickel, zinc and lead. The concentrations of C, P, N, S, Si, Ca, Mg, K, Al, Fe, Mn, Cd, Cr, Cu, Ni, Pb, Zn, Hg and Ti were estimated on the basis of 57 grab samples, evenly taken over the whole lake. The samples were analyzed by non-destructive X-ray fluorescence spectrometry, differential pulse anodic stripping voltammetry and electrothermal atomic absorption spectrometry. Distribution maps have been drawn (by means of computer-assisted cartography) for each individual metal to assist in the assessment of the dispersion and accumulation effects. It is very likely that the metal enrichment observed in the sediments in the northeast section of Lake Orta has been caused by focusing phenomena. The mapping, together with statistical treatment of the results and comparison with previous data, has allowed hypotheses to be advanced about the origin and fate of the various pollutants, and suggestions to be made for the recovery of the lake.