  We present RXTE observations covering six normal outbursts of the dwarf nova
SU UMa, the prototype of its class. The outbursts showed consistent X-ray
behaviour with the X-ray count rate dropping suddenly by a factor of our, and
with evidence for a half day delay between the optical rise and the X-ray
suppression. In contrast to SS Cyg, an X-ray flux increase at the beginning of
outburst was not observed, although it is expected from boundary layer models.
The X-ray flux was high and decreasing during quiescence, in conflict with the
disc instability model. The X-ray spectrum of SU UMa was softer in outburst
than during quiescence, and it was consistent with constant reflection.
