Sixty-seven separated minerals and 45 rocks from the Preissac-Lamotte-Lacorne batholiths in western Quebec have been analyzed for Li by a spectrochemical method. The batholithic rocks include amphibolite, hornblende monzonite, biotite granodiorite, biotite-muscovite granite, aplite, and pegmatite. The granites are unusually rich in Li which is mainly contained in biotite and muscovite. The region thus constitutes an Li-rich geochemical province, which is also demonstrated by the presence of spodumene pegmatites of economic value. The source of the spodumene pegmatites has been attributed to fractional crystallization of the batholith magmas on the basis of previous field investigations. The present data substantiate this theory and attempt to explain why the Li-pegmatites are mainly associated with the Lacorne mass.