I present an analysis of trends in ozone since about 1970 and discuss the quality of the ozonesonde data and inconsistencies among data records. In the troposphere there are significant spatial variations in the trends, with largest increases found over Europe (~2% yr-1 throughout the troposphere) and no long-term trend over Canada; there is a small (53¿N) stations of North America. These seasonal losses are consistent with the patterns reported by Stolarski et al. (1992) using TOMS data. Losses are found year round over Syowa, Antarctica, although they are largest in spring. ¿ American Geophysical Union 1994