  During the 1996/1997 outburst of the X-ray transient GRO J1655-40 the Wide
Field Cameras onboard BeppoSAX observed the system with nearly continuous
coverage during some stages of this outburst. On two occasions we find clear
evidence for frequent dipping behaviour, characterized by several absorption
dips occurring within one binary orbit. However, during preceding and following
binary orbits there is no sign of such dips at the same range of orbital
phases. We also collected light curves of absorption dips as seen with other
X-ray instruments. Although the 65 dips that were collected occur preferably
between orbital phases 0.68 and 0.92, there is evidence that the morphology of
the material causing the dips is changing over just one binary orbit. The short
duration (~minutes) and phasing of the dips are discussed in the framework of
models where the stream from the companion star encounters a hot outer rim on
the accretion disk.
