Frequency response analysis often provides a great deal of information about the system response over the entire range of operation. This can be computationally expensive if time-domain methods are used, especially for large structural models. Presence of non-linearity in the system makes it difficult to employ standard frequency response analysis techniques, which are linear in nature. If the system contains mild-nonlinearities and the response of the system can be assumed to be periodic, it is possible to obtain nonlinear frequency response of the system using harmonic balance techniques. This paper presents the application of the harmonic balance method for solving nonlinear structural dynamics problems. To improve robustness of the solution and capture unstable branches, the continuation procedure technique is included along with the harmonic balance method. The method developed has been implemented in MSC Nastran SOL 128.