The experiments were carried out in the Institute of Soil Science and Plant Cultivation, National Research Institute in Puławy (Poland). In the conducted experiments different varieties of lupine were considered as well as various sowing dates. Four cultivars of yellow lupine were considered: Legat and Polo (thermo-neutral), Parys and Markiz (thermo-dependent), as well as three different sowing dates: 1st- early (beginning of April), 2nd- two weeks after the early sowing date, 3rd- four weeks after the early sowing date. Estimation of protein, fat, ash and alkaloids concentration was performed at the Institute of Agrophysics PAS in Lublin by using an Oxford QN 1000 spectrophotometer. The highest yield of protein from unit area was obtained, in both years of the research, for the varieties Polo and Parys which were characterized by high yield of seeds and high protein content. Considerably lower yields were obtained in these conditions in the case of the Legat and Markiz varieties. Sowing date modified the level of protein yields. Together with its delay, yields and protein content in the seeds decreased. Therefore, the highest yields of protein were obtained in objects where lupine was sown moderately early, i.e. at two first dates. The decrease of protein yield in consequence of sowing date delay was less in the case of thermo-neutral varieties of lupine than non-thermo-neutral ones, all the more so as thermo-neutral varieties reacted with less decrease of seed yield in these conditions. Protein content of examined varieties: Legat, Polo, Parys and Markiz did not show any big differentiation in respect of tested amino acids concentration. The differ-ences in amino acid composition between particular varieties were in the range of 2-11%. Concentration of all examined amino acids increased together with delay of sowing date. The least changes under the influence of this factor concerned tyrosine, and the greatest – valine.