In April 1995 the Global Ozone Monitoring Experiment (GOME) was launched aboard the European Space Agency's second European Remote Sensing (ERS-2) satellite. GOME is a nadir-viewing spectrometer measuring solar radiation backscattered by the system Earth-atmosphere in the ultraviolet and visible spectral range. For the retrieval of ozone vertical distributions from GOME measurements the Full Retrieval Method (FURM) has been developed. It is based on the optimal estimation approach and on results from information theory. The joint retrieval of the ozone profile and several additional parameters (e.g., surface albedo) enables the ozone profile retrieval to be extended below the ozone number density maximum. A first validation of the GOME profiles is performed by a comparison with approximately 200 coincident ozonesonde measurements from five European stations. The RMS difference between ozone subcolumn amounts in 10 km layers as measured by GOME and by the sondes is approximately 7–8% in the middle stratosphere and 15–20% in the lower stratosphere. Furthermore, it is demonstrated that information about the ozone content in the troposphere can be retrieved from the GOME measurements.