The effects of lodging and nitrogen rate were studied in a field trial of oilseed rapeBrassica napus L. Lodging decreased seed yield (16%) compared with a frame-raised crop. Yield decreased because of a significant reduction in each of the yield components coupled with a reduced plant population caused by stem breakage at the ground level. Lodging also reduced the final crop dry weight and harvest index. Seed yield was also lower when 200 kg ha(-1) nitrogen was applied than with 400 kg ha(-1). A general decrease in pod number m(-2), seed nuber pod(-1) and seed weight caused the lower yields. The use of 400 kg ha(-1) of nitrogen changed the contribution of the terminal raceme and individual branches with respect to seed yield. Seed nitrogn content and nitrogen yield increased at the 400 kg ha(-1), lowering both seed oil content and oil yield.