A linear stability analysis of the governing equations for the bed and flow topography in straight alluvial channels is treated. The flow is described by a horizontal two-dimensional model, but secondary flow due to curvature of the streamlines is included. Further more knowledge about secondary flow inertia achieved in recent years is incorporated. The analysis suggests that secondary flow plays an important role for the development of meander bends in relatively narrow channels. The results of the stability analysis are compared with some sandflume data. The agreement is unsatisfactory, but the discrepancy can be explained by insufficient knowledge about the secondary flow properties. However, the sandflume data and the results of the stability analysis exhibit the same trends with respect to dependence of width-depth ratio and alluvial roughness, i.e. increasing width-depth ratio as well as increasing roughness coefficient promotes the formation of alternate bars.