We report a search for effects of large extra spatial dimensions in p (p) o
ver bar collisions at a center-of-mass energy of 1.8 TeV with the DO detect
or, using events containing a pair of electrons or photons. The data are in
good agreement with the expected background and do not exhibit evidence fo
r large extra dimensions. We set the most restrictive lower limits to date,
at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for
several formalisms and numbers of extra dimensions.