This paper presents a novel frequency-domain approach for distributed harmonic analysis (DHA) of a multi-area interconnected electric power system within restructured environment. The proposed approach is based on a decentralized structure in which harmonic analysis of an area is independently conducted, even with limited available data, via local computing resources. The large-change sensitivity (LCS) concept is then applied in a secure platform to account for the effects of whole network to each single area of the interconnected power system. Frequency-dependent models of system elements accompanied by any existent harmonic assessment method can be utilized for harmonic penetration calculation. The proposed DHA approach is capable of finding exact values as those of the interconnected system using TCP/IP communication facility. Moreover, it allows operator of a utility to independently conduct DHA within a restructured power network. The developed method is implemented in an existing software package and applied to several networks including the IEEE 118-bus test system. (C) 2016 Elsevier B.V. All rights reserved.