Two methods of increasing the energy content of yellow lupin seeds for growing pigs were studied: (1) dehulling of seeds and (2) the addition of fat to diets containing lupin. An additional aim of the study was to determine the effectiveness of lysine and methionine supplementation of lupin-containing feeds. Experiment I, lasting 39 days, was carried out on 25 barrows with an average body weight of 27 kg. Experiment II was carried out on 25 barrows weighing from 30 to 100 kg. In both experiments, the animals were fed individually using isoprotein feed mixtures. Daily weight gain, feed utilization, nutrient digestibility, nitrogen balance and, in experiment II, carcass quality were determined. Supplementing lupin-containing mixtures with lysine and methionine increased daily weight gain by 10% and nitrogen retention by 21 % (Experiment I). The addition of fat to cereal-lupin diets led to 7.6% higher daily weight gains in Experiment I (P < 0.05), and 14.2% higher gains in Experiment II (P<0.01) over the entire period of the experiment. The use of deulled lupin seeds increased weight gain by 4.8% (P>0.05) in Expt. I and by 13.5% (P<0.01) in Expt. II. It was found that yellow lupin can completely replace soyabean oilmeal in the diets for pigs of over 30 kg body weight, under the condition that the diets are balanced in respect to lysine and methionine. The nutritive value of diets containing mostly barley and yellow lupin can be improved by adding fat or dehulling seeds.