Immediate effect of two rates of gel-forming polymer Viterra (0.5 g kg-1 i 1 g kg-1) on soil aggregation and aggregate water stability in lessivé soils developed from loess, subjected to surface water erosion, were investigated in a field experiment. Investigated soils represented moderately eroded lessivé soil and very severely eroded soil (initial pararendzina). The results obtained prove that application of these dosage rates of Viterra significantly reduced unfavourable clodiness and increased the content of air-dry aggregates of 1-5 mm and 0.25-1 mm in diameter in surface layer of eroded soils. The conditioned soils were characterized by significantly higher content of water-stable aggregates of 0.25-10 mm in diameter, mainly of 1-10 mm and 1-5 mm. Most effective was the rate of 1 g kg-1 of hydrogel.