Here we present a validation of IASI vertical ozone profiles. This has been done using balloon ozonesonde data, which have a vertical resolution of about 100 m and measures ozone from the surface up to an altitude of about 30 km. IASI vertical ozone profiles are given as partial ozone columns [in DU per layer] between varying pressure levels. To validate the satellite derived ozone layers with the balloon ozone sounding data we integrate the ozone measured by the balloon ozone soundings between the corresponding IASI pressure levels. We take into account the IASI averaging kernels in our analysis in order to smooth the ozonesonde data towards the resolution of the satellite data.