This paper presents the first measurement of inclusive J/psi production cro
ss section in the forward pseudorapidity region 2.5 less than or equal to \
eta(J/psi)\ less than or equal to 3.7 in p (p) over tilde collisions at roo
t s = 1.8 TeV. The results are based on 9.8 pb(-1) of data collected using
the DO detector at the Fermilab Tevatron Collider. The inclusive J/psi cros
s section for transverse momenta between I and 16 GeV/c is compared with th
eoretical models of charmonium production. [S0031-9007(98)08183-6].