  We present a search for gravitational arcs in a sample of X-ray luminous,
medium redshift clusters of galaxies. The sample of clusters is called
ARCRAIDER, is based on the ROSAT Bright Survey (RBS) and fulfills the following
criteria: (a) X-ray luminosity Lx>=0.5x10^45erg/s (0.5-2keV band), (b) redshift
range 0.1<=z<=0.52, (c) classified as clusters in the RBS, (d) not a member of
the Abell catalogue and, finally, (e) visible from the ESO sites La
Silla/Paranal (declination \delta<=20deg). In total we found more than 35
(giant) arc/arclet candidates, including a possible radial arc, one
galaxy-galaxy lensing event and a possible quasar triple image in 14 of the 21
clusters of galaxies. Hence 66% of the sample members are possible lenses.
