The fracture surface roughness was determined for five highly deformable polymers (styrene-butadiene rubber, two ethylene-propylene rubbers, low density polyethylene and plasticized polyvinyl chloride) as a function of rate and temperature. The mechanical hysteresis for the same materials was also measured as a function of rate, temperature and strain amplitude. Although the surface roughness does not correlate with crack velocity, it does so uniquely with the effective hysteresis in the material surrounding the propagating crack. A simple physical explanation is advanced for the universal dependence of roughness on hysteresis in these materials.