The aim of the research was to compare the morphological features, influenced the competitive ability against weeds, of some winter wheat varieties cultivated in organic system. The study was conducted in the years 2004-2005 at the Experimental Station of Institute of Soil Science and Plant Cultivation - State Research Institute in Osiny. On the experimental fields used in ecological way for 11 years 5-field crop rotation is realised. In the field of winter wheat some varieties are sown in pure sowing (Kobra, Mewa, spelt wheat: variety Schwabenkorn) and the mixture (Kobra+Kris+Tonacja). Weed control was based on crop rotation and mechanical weed control using a weeder. The study on the competitive ability of varieties including plant height, tillering, total leaf area, leaf area index (LAI), mean foliage tip angle (MTA), number of plants and ears and wheat dry matter was done and weed infestation was assessed. The spelt (variety Schwabenkorn) was the highest and had the biggest values of tillering, total leaf area and leaf area index (LAI). Kobra and mixture of varieties showed less favourable parameters of growth and development, which influenced the competitiveness against weeds. The level of weed infestation was the highest in Kobra canopy and mixture of varieties and the lowest in the spelt and Mewa.