We present new sub-millimeter data of Herbig Ae/Be stars taken with single dish telescopes in Chile in order to search 
for continuum and gas emission around these system. We detect 12CO emission around at least  two systems, as well as the 
870 micron continuum. The new sub-mm data is input into the radiative transfer code MCFOST (Pinte et al. 2006) to produce 
disk models that fits the entire SEDs. The models reproduce well the observed CO line profiles, constraining the geometry 
and mass of their circumstellar disks.