Cryogenic collection of water vapor and subsequent volumetric measurement in the laboratory were used to measure stratospheric water vapor concentrations. Also measured were the deuterium and tritium content of the water samples. The isotopic measurements provide information not only on contamination during sampling, but also on the origin or previous history of the water vapor. The stratospheric H2O profiles show an increase with altitude which is weak for the high latitudes and steeper around 30¿N. Profiles of total hydrogen (the sum of H2O, CH4, and H2) show no significant vertical gradients indicating that the H2O increase was essentially caused by the vertial decrease in the CH4 mixing ratio. Isotopic measurements from one flight over Alaska indicate the same.