  We present the results from the high resolution Chandra observation of the
Cartwheel galaxy. Many individual sources are resolved in the image, mostly
associated with the outer ring. All detected sources have a very high X-ray
luminosity ($\geq 10^{39}$ erg s$^{-1}$)that classifies them as Ultra Luminous
X-ray sources (ULX). The brightest of them is possibly the most luminous
individual non-nuclear source observed so far, with L$_X \sim 10^{41}$ erg
s$^{-1}$ (at D=122 Mpc). The spatial extent of this source is consistent with a
point source at the Chandra resolution. The luminosity function of individual
X-ray sources extends about an order of magnitude higher than previously
reported in other galaxies. We discuss this in the context of the "universal"
luminosity function for High Mass X-ray Binaries and we derive a Star Formation
Rate higher than in other starburst galaxies studied so far. A diffuse
component, associated with hot gas, is present. However, deeper observations
that we will obtain with XMM-Newton are needed to constrain its properties.
