Methods for speeding the collection and analysis of macroinvertebrate samples are urgently needed to increase sampling precision and to reduce cost. The cycle sieve described in the present paper is practical for most freshwater work from small boats because it is light and portable, the major components are available commercially, and the parts are easily assembled. Because the samples are washed by hand at boatside, no special fixtures or energy sources are required. The entire sample is washed at one time, without risk of losing material, and the sieving effort is standardized.