Abstract : The most well known result of homogeneous isotropic turbulence is Kolmogorov’s 5/3-law , written down from a physical picture and a dimensional argument in 1941. For turbulence in a stratified fluid Bolgiano and independently Obukhov proposed a 11/5-law in 1959. Over the last fifteen years a large number of numerical and experimental investigations have failed to discern any clear-cut scaling.