due to its nutritional characteristics, lupinus exaltatus is considered as an alternative source of animal feed in temperate regions. however, the presence of quinolizidine alkaloids in different plant organs limits its consumption. the composition and concentration of alkaloids in leaves, stems, flowers, and inmature fruits of l. exaltatus was determined in five different phenological stages with the final purpose of suggesting alternatives for its management and use as forage. plants were sowed in pots and at each phenological stage six plants were harvested and separated in roots, stems, leaves, flowers, and inmature pods that were air dried to constant weight. each organ was analyzed for alkaloid composition and content by capillary gas chromatography- mass spectrometry (gc-ms). in each phenological stage and in all organs the alkaloid profile was characterized by the presence of six major alkaloids: epiaphylline aphylline, a-isolupanine, lupanine, dehydro-oxosparteine and 3-b-hydroxylupanine. although the alkaloid profile was constant, the total concentration in the different organs showed a significant variation (0.31-2.1%) in the different phenological stages. in general, after the five growth stages the stems showed the lowest average total alkaloid concentration (0.63%) whereas inmature pods had the highest total alkaloids (1.95%). lupanine was the major alkaloid in stems and fruits. although alkaloids with the highest toxicity (sparteine, anagyrine and ammodendrine) were not detected, the results indicate that the major risk for intoxication could occur during pod growth and seed ripening, due to high total alkaloid content and larger abundance of lupanine in immature fruits.