The unique procedure for measuring the total ozone content in the atmosphere with the help of the Pion solar uv spectrometric ozonometer is discussed. The results of intercomparison of the Pion readings and the data obtained with the Brewer No. 45 and Dobson No. 107 spectrometers are presented for the spring–fall seasons of 1991. It is shown that the accuracy of the average daily measurements performed with the Pion ozonometer is close to the accuracy of readings of the Brewer and Dobson instruments.