  We show that atmospheric neutrinos can provide a sensitive and robust probe
of CPT violation (CPTV). We perform realistic event-rate calculations and study
the variations of the ratio of total muon to antimuon survival rates with $L/E$
and $L$ ($L$ $\equiv$ baseline length, $E$ $\equiv$ neutrino energy) in a
detector capable of identifying the muon charge. We demonstrate that
measurements of these ratios when coupled with the significant $L$ and $E$
range which characterizes the atmospheric neutrino spectrum provides a method
of both detecting the presence of such violations and putting bounds on them
which compare very favourably with those possible from a future neutrino
factory.
