An apparatus for the rapid measurement of large populations of cereal coleoptiles is described. It has application in seedling evaluation and the study of factors affecting early seedling growth. The seedlings are grown in shallow trays and passed through a photoelectric counter which records the number of coleoptiles present at successive 1 cm intervals of height above the substrate. A frequency distribution for seedling height is obtained from the difference between counts at consecutive levels, and the mean height from the total at all levels. The estimate of mean height is typically accurate to within about 1 mm for batches of 200 seedlings. The measurements are non-destructive and may be repeated at intervals to obtain a growth curve.