  We discuss the potential of the eROSITA telescope on board the
\emph{Spectrum-X-Gamma} observatory to detect gamma-ray burst (GRB) X-ray
afterglows during its 4-year all-sky survey. The expected rate of afterglows
associated with long-duration GRBs without any information on the bursts proper
that can be identified by a characteristic power-law light curve in the eROSITA
data is 4--8 events per year. An additional small number, $\lesssim 2$ per
year, of afterglows may be associated with short GRBs, ultra hard (GeV) GRBs
and X-ray flashes. eROSITA can thus provide the first unbiased (unaffected by
GRB triggering) sample of $\lesssim 40$ X-ray afterglows, which can be used for
statistical studies of GRB afterglows and for constraining the shape of the GRB
$\log N$--$\log S$ distribution at its low-fluence end. The total number of
afterglows detected by eROSITA may be yet higher due to orphan afterglows and
failed GRBs. The actual detection rate could thus provide interesting
constraints on the properties of relativistic jets associated with collapse of
massive stars. Finally, eROSITA can provide accurate ($\lesssim 30"$)
coordinates of newly discovered afterglows within a day after the event, early
enough for scheduling further follow-up observations.
