The stability of hierarchical lamellar morphologies formed in ABC star triblock copolymers, is studied using the self-consistent mean-field theory. The hierarchical lamellae consist of repeating period of the largest block A-formed layer and B/C coformed layer where B and C domains are arranged alternatively. An angle, which is used to characterize the shifting magnitude between two neighbor B/C coformed layers, varies from 0 to 180 degrees. By comparing the free energy among the lamellar morphologies with various shift angle, their relative stability is analyzed. Our results show that the morphology with larger shift has lower entropic energy and higher internal energy. In general, the morphology with the largest shift of 180-degree is stable compared with those with smaller shift as the entropic energy dominates the internal energy. However, the relative stability can be tuned by the interactions among the three. components as well as their relative compositions. PACS numbers: 61.25.Hq, 64.60.Cn, 64.75.+g. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1101-1109, 2010