  We report on an analysis of XMM-Newton data from the neutron star low mass
X-ray binary (LMXB) Serpens X-1 (Ser X-1). Spectral analysis of EPIC PN data
indicates that the previously known broad iron K$\alpha$ emission line from
this source has a significantly skewed structure with a moderately extended red
wing. The asymmetric shape of the line is well described with the laor and
diskline models in XSPEC and strongly supports an inner accretion disk origin
of the line. To our knowledge this is the first strong evidence of a
relativistic line in a neutron star LMXB. This finding suggests that the broad
lines seen in other neutron star LMXBs likely originate from the inner disk as
well. Detailed study of such lines opens up a new way to probe neutron star
parameters and their strong gravitational fields. The red wing of the iron line
from Ser X-1 is not as broad as that observed from some black hole systems.
This is not unreasonable for a neutron star system, as the accretion disk has
to terminate at or before the hard stellar surface. Finally, the inferred
source inclination angle in the approximate range 40 degree to 60 degree is
consistent with the lack of dips and eclipses from Ser X-1.
