Vertical profiles of the rate of linear change (trend) in the altitude range 15–50 km are determined from decadal O<sub>3</sub> time series obtained from SCIAMACHY/ENVISAT measurements in limb viewing geometry. The trends are calculated by using a multivariate linear regression in the zonal bands 5° S–5° N (tropics), 50–60° N, and 50–60° S (mid- to high latitudes). Seasonal terms, the quasi-biennial oscillation, and solar cycle variations are accounted for in the regression. In the tropics, positive trends between 15 and 30 km and negative trends between 30 and 35 km are identified. Moderately positive O<sub>3</sub> trends are found in the upper stratosphere of the tropics and midlatitudes. The explanation favoured for the observed positive and negative trends in the tropical lower and middle stratosphere is NO<sub>x</sub> chemistry. Comparisons between SCIAMACHY and EOS MLS in the tropics and at midlatitudes show good agreement. In the tropics, measurements from OSIRIS/Odin and SHADOZ are analysed resulting in very similar vertical profiles of the rate of linear change of O<sub>3</sub>. Observed trends in the stratospheric column derived from integrated SCIAMACHY limb O<sub>3</sub> profiles and nadir total columns are found to be consistent.