Subtropical dry zones, located in the Hadley cells’ subsidence regions, strongly influence regional climate as well as outgoing longwave radiation. Changes in these dry zones could have significant impact on surface climate as well as on the atmospheric energy budget. This study investigates the behaviour of upper tropospheric dry zones in a changing climate, using the variable Upper Tropospheric Humidity (UTH), calculated from climate model experiment output as well as from radiances measured with satellite-based sensors. The global UTH distribution shows that dry zones form a belt in the subtropical winter hemisphere. In the summer hemisphere they concentrate over the eastern ocean basins, where the descent regions of the subtropical anticyclones are located. Recent studies with model and satellite data have found tendencies of increasing dryness at the poleward edges of the subtropical subsidence zones. However, UTH calculated from climate simulations with 25 models of the Coupled Model Intercomparison Project Phase 5 (CMIP5) shows these tendencies only for parts of the winter hemispheric dry belts. In the summer hemisphere, even though differences exist between the simulations, UTH is increasing in most dry zones, particularly in the South and North Pacific. None of the summer dry zones is expanding in these simulations. Upper tropospheric dry zones estimated from observation data do not show any robust signs of change since 1979. Apart from a weak drying tendency at the poleward edge of the southern winter hemispheric dry belt in infrared measurements, nothing indicates that the subtropical dry belts have expanded poleward.