In this study, indentation of circular metal tubes during lateral compression process between a V-shape indenter and a rigid platen is investigated by the experimental and theoretical methods. A new analytical model of plastic deformation in the circular metal tubes during the process is introduced and the theoretical analysis is performed based on the energy method and several relations are derived to predict the average lateral load and absorbed energy by the tubes as functions of lateral displacement, geometrical characteristics, and material properties of the tube. Also, to verify the theoretical analysis, some lateral compression tests were performed on circular metal tubes and the results were compared with the corresponding theoretical predictions. The comparison shows a good agreement between the theoretical predictions and experimental results and so, it confirms general form of the present theoretical formula. Also, effects of each geometrical dimension and material properties of the tubes on the average lateral load are investigated using the experimental measurements and the theoretical predictions.