The results obtained on the basis of the crop-rotation long-term experiments conducted from 1972 to 1997 on a good wheat soil complex at the Experimental Station in Błonie-Topola and from 1970 to 1997 on a very good rye soil complex at Experimental Station in Grabów were used in the paper. The forecrop value of oats with other plant species for winter wheat and spring barley was estimated. The productivity of winter wheat sowing after oats in cereal crop rotations was only 3-7% lower than winter wheat cultivated after non-cereal forecrops (potato, pea). Similar dynamics of the winter wheat grain yields increase in the analogous position in the crop rotation was stated on an average for 26 years. The forecrop value of oats for spring barley is good. In such agricultural conditions significantly higher than after cereal forecrops productivity is obtained. However such a sequence should be planned for shorttime periods because of the possibility of multiplying in the soil great quantities of parasitical nematodes (Heterodera avenae).