Recently, non-axisymmetric convection in vertical directional solidification experiments has been observed. It has been suggested that the asymmetry is due to lack of azimuthal symmetry in imposed temperature and that the flow asymmetry will decrease with increasing velocities. Motivated by these observations we have examined the consequences of deviations from axisymmetric wall temperature conditions in a vertical differentially heated cylinder. We show that the degree of flow asymmetry depends on the ratio, Aθ, between the amplitudes of the maximum azimuthal and vertical temperature differences, and that for a fixed value of this ratio the flow asymmetry increases with increasing flow velocity (Rayleigh number). © 1992.