The spectrum of the vertical temperature gradient is computed for a number of "typical" 50-m long profiles from the upper 200 m of the ocean. Most of the variance occurs in the microstructure range, between approximately 1 and 100 cycles/m; there is normally a spectral maximum near 10 cycles/m. The shape of the spectra for the range 10–100 cycles/m agrees well with that predicted for sharp interfaces that have been smoothed by thermal diffusion.