  We compare the count-rates of active binaries observed by Einstein and ROSAT.
We find significant evidence for short-term variability (approx 0.32) and
marginal evidence for a larger variability at longer timescales (approx 0.38).
Modeling this excess as cyclic variability, we place an upper limit on the
relative amplitude of the cyclic component (I_cyc/I_min < 4) for active
binaries, significantly less than the variations seen in the Solar X-ray output
over the Solar cycle.
