Daily or biweekly precipitation samples have been collected at various sites on the island of Hawaii since 1974. The elevations of the sites ranged from sea level to 3400 m. Samples were analyzed on the day of collection for pH and conductivity. Detection of major anions, such as sulfate and nitrate, were made on selected samples during the period. The pH data show a progressive increase of acidity with elevation. The sea level site averaged pH 5.2, in contrast to the sites above 2500 m, which averaged pH 4.3. It is postulated that the increase in acidity at higher levels might be explained by acidic materials, either natural or man-made, being transported over long distances in the mid-troposphere and being scavenged in the rain of the Hawaiian islands.