  We have developed radiative transfer models of the radio emission from
colliding-wind binaries (CWB) based on a hydrodynamical treatment of the
wind-collision region (WCR). The archetype of CWB systems is the 7.9-yr period
binary WR140, which exhibits dramatic variations at radio wavelengths.
High-resolution radio observations of WR140 permit a determination of several
system parameters, particularly orbit inclination and distance, that are
essential for any models of this system. A model fit to data at orbital phase
0.9 is shown, and some short comings of our model described.
