  Radio recombination lines (RRL) at 8 GHz and 15 GHz detected from four
starburst galaxies are shown to arise in compact high density HII regions,
which are undetectable below ~4 GHz. Detection of an RRL at 1.4 GHz towards one
galaxy and upper limits in the other three are consistent with the presence of
an equal amount of low density diffuse gas. Continuum flux density measurements
using the GMRT will be important in constraining the properties of the diffuse
gas.
