Soybean seed size can have a major effect on the quality of seeds. Beside the effect that seed size has on 1000-grain weight, it can also affect other seed quality parameters. Some authors suggest it can be expected that larger seeds have better quality. Seeds with higher content of reserve nutrients provide better developed plants, so it is possible to expect higher yields. Since the soybean seed does not have the minimum dimension of certified seed prescribed by law, it is necessary to examine the minimum size of seed that gives good enough results at planting, growth and development of plants. On the basis of these indicators, set up of cleaners and selection of work sieves cleaners during processing of soybean seed should be accessed. Soybean has a roundish shape, so it is possible to calibrate by a simple procedure using sieves of different sizes and openings. The effect of certain sizes on the soybean seed germination and initial growth of seedlings of varieties which are characterized by different seed sizes was tested in this work. On that occasion the varieties Balkan, Victoria and Trijumf, which were developed at the Institute of Field and Vegetable Crops in Novi Sad were used. Dry matter content in the plant was used as an indicator of initial seedling growth. It was found that the dry matter content of seedlings increases with larger sizes, compared to dry matter content of smaller sizes. Thus, the lowest value was recorded in the variety Trijumf, for the size of 4.0 to 4.5 mm 4.7 g, while the highest value was recorded also in the variety Trijumf for the size of 6.0 to 6.5 mm 8.1 g. In addition, it was observed that the germination of seed of different sizes has different values. The lowest values were recorded in Balkan variety for the size of 4.0 to 4.5 mm 64%, while the highest germination was recorded in the variety Victoria for the size of 5.5 to 6.0 mm 85%.