The objects of the study were plants of 14 varieties of spring durum wheat Triticum durum Desf. of Saratov selection, approved for use in the period from 1975 to 2014. The study of the size of starch grains was carried out on micro-preparations of macerate of endosperm fragments from the area of the crest, scutum and groove. To automate the process of measuring starch grains, the OpenCV computer vision library for the Python programming language was used. The study analyzed granulometric composition of the endosperm of grain varieties with a balanced type of morphogenetic systems in terms of ear productivity elements and high values of productivity indices: Canadian, Mexican, and linear density index. It was found that the Luch 25 variety, which in 2020 belonged to the balanced in all main indicators of the morphogenetic productivity index (MIP) – the number of spikelets, the number of grains and their weight and has the highest value of the Canadian productivity index, is characterized by a minimum, among the studied types, variation in the diameter of starch grains (in the whole grain). The varieties Nikolasha and Zolotaya Volna, which in 2021 were considered balanced in all the main indicators of MIP, are characterized by a minimum diameter of starch grains (in general, by grain). Varietal differences in the average diameter of starch grains in the endosperm of the grain were revealed. The paper presents information on the granulometric composition of the starchy endosperm in the area of the crest, groove (middle part), and scutellum. A comparative analysis of the representation of small, medium and large starch grains in different parts of the grain of each of the objects of study was carried out. Differences in the size of starch grains in the endosperm of mature durum wheat grains of Saratov varieties have been established, which indicates the variety specificity of this indicator.