  The K2K experiment has presented the first results on the observation of
nu_mu. They show a depletion compared to the expectations and are consistent
with neutrino oscillations with a mass-splitting in the range favoured by the
Super-Kamiokande atmospheric neutrino measurements. Here we examine the extent
by which the range of Delta m^2 obtained from the K2K measurements can vary due
to the uncertainties in the flux, cross-section, and detector efficiency.
