We show, by use of angle-resolved photoemission spectroscopy, that underdoped Bi2Sr2CaCu2O8+δ appears to have a large Fermi surface centered at (π, π), even for samples with a Tc as low as 15 K. No clear evidence of a Fermi surface pocket around (π/2, π/2) has been found. These conclusions are based on a determination of the minimum gap locus in the pseudogap regime Tc &lt
T &lt
T*, which is found to coincide with the locus of gapless excitations in momentum space (Fermi surface) determined above T* . These results suggest that the pseudogap is more likely of precursor pairing rather than magnetic origin. © 1997 American Physical Society.