Experiments have been conducted to determine the effect of density stratification upon certain characteristic features of so-called Taylor columns. The interior structure of the homogeneous Taylor column is first of all described and compared with flow patterns obtained when the fluid is stratified. Qualitative features of the horizontal and vertical motion (in particular, the attenuation with height of the distortion created by the obstacle) are then described for values of the stratification parameter S (defined as S = N/2 Ω, whereN and Ω are the Brunt-Väisälä and rotation frequencies respectively) in the range 0 ⩽ S ⩽ 0·24. The effect of density stratification upon, specifically, the length of the column is then described. A working definition for the existence of a Taylor column in a given experimental situation is formulated, enabling the strength of the column to be quantified at a particular height above the obstacle. Using this method the column length is measured as a function of S in the range 0 ⩽ S ⩽ 0·24. It is shown that even very slight stratification is sufficient to produce noticeable modification of all aspects of the flow. In particular, the column length is considerably reduced by weak stratification. © 1972, Cambridge University Press. All rights reserved.