This study evaluated the diversity of weed communities in winter wheat (Triticum aestivum L.) grown under a four-field crop rotation and a 36-year monoculture within an experiment established using a randomised block design (25 m × 6 m). Weed communities in both systems comprised species from four syntaxonomic classes, with the most abundant belonging to Stellarietea mediae. The weed commu- nity comprised 27 species in the crop rotation and 23 species in the monoculture. Apera spica-venti and Avena fatua predominated in both systems, accounting for 55.6% and 74.5% of the total weed populations, respectively. Crop succession in both systems influenced phytosociological indices. Shannon’s diversity index and the richness index were significantly higher in the crop rotation than in the mono- culture. Conversely, the dominance, similarity, and evenness indices calculated for the monoculture indicated the presence of dominant species within its weed com- munity. These findings confirm earlier observations of the predominance of a few weed species in communities best adapted to the applied cropping systems and habitat conditions.