  The presence or lack of eclipses in the X-ray lightcurves of ultraluminous
X-ray sources (ULXs) can be directly linked to the accreting system geometry.
In the case where the compact object is stellar mass and radiates
isotropically, we should expect eclipses by a main-sequence to sub-giant
secondary star on the recurrence timescale of hours to days. X-ray lightcurves
are now available for large numbers of ULXs as a result of the latest
XMM-Newton catalogue. We determine the amount of fractional variability that
should be injected into an otherwise featureless lightcurve for a given set of
system parameters as a result of eclipses and compare this to the available
data. We find that the vast majority of sources for which the variability has
been measured to be non-zero and for which available observations meet the
criteria for eclipse searches, have fractional variabilities which are too low
to derive from eclipses and so must be viewed such that theta =< acos(R*/a).
This would require that the disc subtends a larger angle than that of the
secondary star and is therefore consistent with a conical outflow formed from
super-critical accretion rates and implies some level of geometrical beaming in
ULXs.
