A precipitation sampling network designed specifically to optimize sample collection and handling for trace analysis was established at Walker Branch Watershed (WBW), Tennessee, to measure the atmospheric input of trace elements. The network consists of 6 rain activated wetfall collectors of the AEC-HASL design which have been modified in order to minimize trace element contamination. Wetfall has been collected through a combination of event and continuous sampling at 4 throughfall, 1 ground level incident, and 1 above canopy incident precipitation sites. Trace metal analyses were performed by graphite furnace atomic absorption spectroscopy without preconcentration to reduce the chance of contamination. Sulfate-S was determined by a modified methylthymol blue technique. Both methods are applicable to trace level rainwater analysis. Preliminary data for water year 1975-76 yielded weighted mean concentrations (and coefficients of variation) for Cd, Pb, Zn, and SO4-S in incident precipitation as 0.89 (108 percent), 1.5 (97 percent), 5.5 (54 percent), 7.1 (111 percent), and 840 (48 percent) .mu.g/1, respectively. For storm events spatial effects on incident and throughfall rain chemistry were significant. Temporal effects on chemistry were also significant at some incident and throughfall sites. In comparison with published trace element concentrations in rain, the levels at WBW were closer to those measured at rural and remote forested locations than those observed near industrial or urban centers.