A set of drop size distribution data is presented covering a wide range of sprinkler types including single nozzle impact sprinklers with straight bore and square nozzles, and sprayheads with various types of deflector plates. Drop sizes were measured by the laser-optical method and comparisons with other types of drop size measurement techniques are presented. Distributions are parameterized with an exponential function, and a method is provided to estimate the parameters given the sprinkler type, nozzle size, and pressure head. Keywords. Irrigation, Sprinklers, Drop size. S prinkler irrigation can be defined as any irrigation system which distributes water as discrete droplets through the air. The variety of sprinkler devices available has increased dramatically in recent years, from the conventional single or double nozzle impact sprinkler with many types of nozzles to various types of deflection-plate sprinklers which influence the drop sizes and water distribution patterns over a wide range of flow rates and pressures. Accurate knowledge of drop size distributions for sprinklers is important because evaporation and drift losses are controlled by the extreme small size ranges and drop impact energy on the soil is determined primarily by the largest size ranges. Selection of a specific sprinkler package for a sprinkler system operating on particular soil, slope, crop, and climate conditions will be aided by knowledge of the drop sizes. Several articles have been published describing the drop size distributions of specific types of sprinklers (Kohl, 1974; Kohl and DeBoer, 1984; Solomon et al., 1985; Kohl and DeBoer, 1990). The reported data were collected using pellet, stain, and photographic methods. This article presents additional data using a laser-optical method compared with some distributions determined by some of the previously used methods, so that the entire body of published data is more comparable. The main objective is to parameterize the data and present a method to predict the parameters as a function of nozzle size and pressure.