Structure of stimulated emission spectra of noble gas monohalogenide molecular lasers is considered. Spectrum of KrF lasing on bound-to-free transitions is reported. Fine structure of stimulated emission spectra of molecules with shallow potential well in the ground state is considered by the example of XeCI and XeF molecules. The structure is due to rotations in XeCl and XeF. Influence of the active medium parameters (pressure, mixture composition) on the structure of XeF molecule stimulated emission spectrum structure as well as spectral performances of emission of XeF laser pumped by powerful electron beam and pulsed electric discharge are considered. The nature of the lasing spectrum in the region near 350 nm is discussed. The report is based mainly on the authors' studies.