Atmospheric concentration in the marine boundary layer and direct deposition measurements of total nitrate and ammonium for an eastern South Pacific coastal site near Valparaiso, Chile, were carried out during the period January 1992 through March 1993. Concentrations in air for both nitrogen forms exhibit a seasonal pattern with low values in summer and a pronounced increase in winter, having a mean annual concentration of 32.6 nmol m-3 for total nitrate and of 44.8 nmol m-3 for total ammonium. Wet deposition is characterized by annual precipitation weighted concentrations of 6.0 and 8.1 μmol dm-3 for nitrate and ammonium, respectively. The main factor regulating wet deposition for both nitrate and ammonium is rainfall amount, so that changes in precipitation amount alone originated by climatological factors can produce changes in their relative deposition levels. Existing climatological pattern determines an overall dominance of dry over wet deposition, with totals of 12.9 and 7.34 mmol m-2 per year, the reduced forms of nitrogen being generally more abundant. ¿ American Geophysical Union 1996