Spectra of six main sequence stars with spectral types from F0 to G8 were obtained with the IUE long wavelength spectrograph at high resolution. Four or more spectra of each object were taken over a period of 3.5 years, supplemented by archive spectra from IUE of the same type. Quantitative analysis of the Mg II h and k emission cores from these spectra was performed to search for sporadic or periodic variability. No variations the + or - 10% level set by the statistical fluctuations within each set of spectra occur for any object. Even the limited photometric accuracy claimed here is not guaranteed among spectra which vary in exposure time by more than 15%. This situation for all IUE LWR spectra can be improved only by solving the problem of background subtraction.