A field investigation was carried out on lessive soil developed from loess. Status and level of weed infestation of two winter wheat cultivars (Rysa and Mobela) grown as short-lasted continuous crop and in crop rotation were determined. Increase of number and weight of weeds was proved under wheat cultivated in continuous cropping system, in spite of well chosen herbicides application. Short-lived weeds infested the cereal mostly: Apera spica-venti, Viola arvensis, Stellaria media and Capsella bursa-pastoris dominated there in continuous cropping system. Rysa cultivar was more susceptible to weed invasion than Mobela cultivar under continuous cropping. Apera spica-venti was particularly abundant in Rysa cultivar canopy, causing the highest dominance index in weed community. Botanical composition of weed communities showed high similarity index under different cultivation system as well as in canopies of the cultivars.