A pot trail and field observations were carried out to assess the pathogenicity of the cyst nematode Heterodera crucifere on cabbage plants (Brassica oleoracea). In the pot experiment H. cruciferae cysts were extracted by the Fenwick can from a soil heavily infested (64 eggs and J2/mL soil) collected from a field in which cabbage plants showed stunted growth and yellowing. An appropriate amount of eggs and juveniles of the nematode were throughly mixed with sterilised sandy soil to obtain population density in a geometric scale from 0 to 512 eggs and J2/mL soil (0, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256 and 512). Then, the soil was used to fill clay pots (V=700 mL). A cabbage seedling (cv. Aviso) was transplanted in each pot and grown for 60 days in a glasshouse at 20 °C. For each nematode population density 6 resplications were considered. During the experiment plants were maintained in the glasshouse randomizing the position of the blocks and at the same time repositioning each plant within a block every week, to avoid a block position effect and at the same time the factor position of the plant within the block. Plants received all the necessary maintenance (irrigation, fertilization, etc.). At the end of the experiment plants were uprooted to assess top plant weight and the soil was dried at room temperature. Cysts were extracted from soil (200 mL dried soil) by the Fenwick can to determine their eggs and J2 content/mL soil (Pf). Data of fresh top weight from the experiment were fitted with the Seinhorst’s model y=m + (1-m) z(P-T) with P>T. A tolerance limit T of 1.50 eggs and J2/mL soil and a minimum relative yield (m) of 70% were determined. The highest reproduction factor (Pf/Pi) was 5 at Pi= 8 eggs and J2/mL soil. The anatomic alterations induced by the cyst nematode on root cabbage were also studied. Cross sections of root cabbage collected in an open field showed syncytiums in nematode feeding sites.