The vibration of chimneys has been studied by a number of investigators. Chimneys are treated as vertical cantilever beams. When the beam vibrates, there are bending, shear and rotatory inertia effects. For beams which are long as compared to the crosssectional dimensions, bending effects are predominant and analysis of such cases has been carried out by Housner (3). Chimneys have been analysed based on the above three effects by Chandrasekharan.(1) The mass of beam in addition to its movement in the lateral direction also exerts a downward force. This vertical load may have some influence on the vibration characteristios of the stacks. The purpose of this paper is to study the extent of the influence of the vertical load on the natural frequencies and mode shapes of the chimneys.