The experiments reported were carried out at the Institute of Soil Science and Plant Cultivation, National Research Institute in Puławy (Poland). In the conducted experiments different varieties of lupin were considered as well as various sowing dates. Four cultivars of blue lupin were considered: Sonet and Graff (thermo-neutral), Boruta and Wersal (thermo-dependent), as well as three different sowing dates: 1st- early (opening of April), 2nd- two weeks after early sowing date, 3rd- four weeks after early sowing date. Estimation of protein, fat, ash and alkaloids concentration was performed at the Institute of Agrophysics PAS in Lublin, using an Oxford QN 1000 spectrophotometer. The response of the lupin varieties to delay in the sowing date was different and strongly depended on the weather conditions. In the year 2004, characterised by weather conditions typical for this region, the delay in sowing date resulted in considerable decrease of the crop yield of both the thermo-dependent and thermo-neutral varieties, however the second class of the plants was less affected. Non-typical weather conditions in the year 2005, characterized with ground-frost on the 2nd and 3rd sowing dates, resulted in vernalization of the seeds sown on those dates so the decrease in the crop yield of all the varieties used was comparable. The blue lupin varieties used in the experiments contained similar amounts of seed crude protein. Crude oil and alkaloid content showed much bigger diversity among the varieties examined. The delayed sowing date brought about a growth in the crude protein and alkaloid content in seeds as well as a distinct decrease in the crude fibre, N-free extracts and ash content. As observed, the date of sowing had considerably smaller influence on the protein content as compared to the amount of the main crop. Delay in the sowing date resulted in an increase of the protein content which accounted for similar protein crop expressed as product of seed crop and the crude protein content. The most favourable dates of sowing in order to obtain the biggest crude protein yield were: 2nd sowing date for thermo-neutral varieties and 1st sowing date for thermo-dependent lupin varieties.