Evidence was obtained that Lupinus angustifolius absorbs less potassium from the soil than L. digitatus or L. luteus, and that it is more susceptible to potassium deficiency. More limited data pointed to a similar difference between species in regard to phosphorus. Observation of lupins and subterranean clover growing together on a potassium-deficient soil indicated that all three lupin species are more tolerant of potassium deficiency than subterranean clover. Possible mechanisms for the species differences are discussed.