High-statistics (>4 x 10(8) counts), room-temperature measurements of
the electron-positron momentum density of La2-xSrxCuO4 have been perfo
rmed for samples with Sr concentrations of x = 0.0, 0.1, 0.13, and 0.2
. These spectra have been analyzed in conjunction with theoretical cal
culations of the electron-positron momentum density. The metallic samp
les show features consistent with the presence of a Fermi surface, but
its evolution with increasing Sr concentration does not follow the pr
edictions of band theory. These results may indicate the effects of el
ectron-electron correlation on the electron momentum distribution in t
he Cu-O plane.