The stratospheric distribution of H2 18O in the 22 to 37 km altitude range has been obtained from balloon-based measurement of far infrared thermal emission spectra with an unapodized spectral resolution of 0.0033 cm-1. The analysis is based on the observed spectra of 9 isolated spectral lines in the 46 to 72 cm-1 region obtained from four complete limb sequences. Comparison of the results with the statistically expected values indicates enhancement in the H2 18O concentrations increasing from 27¿14% at 29 km to 40¿23% at 37 km. No significant enhancement at lower altitudes was observed. ¿ American Geophysical Union 1989