The nutritional value of four cultivars of Lupinus angustifolius L. seeds was investigated. The experiment was conducted on 50 male 16-day-old Ross 308 chickens. The birds were randomly allocated to five dietary treatments (10 replications each). Digestibility was calculated using the difference method. The basal diet and four diets composed of ground lupin seeds (cv. Sonet, Boruta, Graf or Neptun) and the basal diet at a proportion of 25:75 (w/w) were prepared. The birds were fed the diets starting from day 16; on days 19 and 20 of life, excreta were individually collected, then all chickens were sacrificed and ileal digesta was sampled for determination of ileal digestibility. Ileal dry matter digestibility ranged between 56.8% and 62.5% (P < 0.05). The apparent ileal digestibility of aspartic acid, proline, alanine, valine, histidine and lysine was negatively correlated (P < 0.05) with the in vitro water extract viscosity (WEV) of lupin seeds. The apparent metabolizable energy (AME_N) ranged from 7.91 to 9.27 MJ · kg^–1, the lowest was determined for cv. Graf, the highest for Boruta and Sonet. The Graf cultivar was also characterized by the lowest dry matter ileal and total tract digestibility (P < 0.05). The AME_N of lupin seeds was negatively correlated with WEV (r = –0.67; P < 0.05) and raffinose level (r = –0.72; P < 0.05). The relationship between raffinose content and AME_N was linear (P < 0.05).