We propose to make continuum and recombination line
 observations of the radio stars MWC349  and Eta Carinae
 which show STRONG HYDROGEN RECOMBINATION LINE MASER emission
 at millimeter and submillimetre wavelengths. The proposed
 observations will  provide the kinematics and the physical
 properties (density and temperature structure) as a function
 of radius for these ionized stellar winds and will tell us
 to what extent maser emission also affects hydrogen
 recombination lines with  smaller quantum numbers. From the
 full characterization of the ionized stellar winds in these
 sources we will be able to obtain confident mass loss rates,
 and put strong constrains on the driving mechanisms for the
 mass loss in these sources. In particular, for MWC349, the
 data will essential to establish the role of the neutral
 disk in the mass loss processes, to derive its kinematics,
 and to establish the nature of the central star (young or
 evolved).