In this paper, vibration and damping of composite sandwich box column containing viscoelastic layer (VEL) or electrorheological fluid (ER) core with constraining layer and their performance comparison is carried out. The finite element based modal strain energy method is used for predicting the modal loss factor and frequency of laminated composite box columns with integral viscoelastic/ER fluid layers. Effects of core thickness, orientation of the fiber in the base plate and constraining layer, applied voltage and stacking sequence on the vibration behavior of composite sandwich box column for clamped-free boundary condition are studied in the paper. The performance comparison of vicsoelastic layer damping and ER layer damping is also investigated. © 2009 Elsevier Ltd. All rights reserved.