In many seismic design codes and provisions, such as Uniform Building Code and Turkish Seismic Code, prediction of fundamental period of shear-wall dominant buildings, constructed by tunnel form technique, to compute the anticipated seismic forces is achieved by empirical equations considering the height of the building and ratio of effective shear-wall area to first floor area as the primary predictor parameters. However, experimental and analytical studies have collectively indicated that these empirical formulas are incapable of predicting fundamental period of shear-wall dominant buildings, and consequently result in erroneous computation of design forces. To compensate for this deficiency, an effective yet simple formula has recently been developed by Balkaya and Kalkan (2004), and tested against the data from ambient surveys on existing shear-wall dominant buildings. In this study, previously developed predictive equation is modified to include the effects of soil-structure interaction on the fundamental period. For that purpose, 140 shear-wall dominant buildings having a variety of plans, heights and wall-configurations were re-analyzed for four different soil conditions classified according to NEHRP. The soil effects on the foundation were represented by the translational and rotational springs, and their rigidities were evaluated from foundation size and elastic uniform compressibility of soil. Based on the comprehensive study conducted, improved prediction of fundamental period is achieved. The error in predictions on average is about 15 percent, and lending further credibility to modified formula considering soil-structure interaction to be used in engineering practice.