A number of relatively well-isolated lines of the &ngr;3 bands of 16O18O16O and 16O16O18O have been identified in high-resolution solar absorption spectra recorded with the Fourier transform interferometer at the National Solar Observatory on Kitt Peak (elevation 2095 m, latitude 31.9¿N). Based on spectroscopic parameters derived from ozone laboratory spectra recorded with the same instrument, the heavy ozone content of the total column of ozone has been determined from measurements of the equivalent widths of 16O18O16O, 16O16O18O, and 16O3, lines in three solar absorption spectra. Relative to the concentrations in a natural sample of ozone, the analysis indicates 16O18O16O and 16O16O18O isotope abundances of 1.05¿0.07 and 1.11¿0.11 in the total column of atmospheric ozone.