We have conducted a series of empirical studies to examine effect of openings placed within a wall panel such as for penetration upon the load-deflection characteristics of a shear wall. The major purpose of the study is to examine effect of openings within a wall panel upon structural properties of a heavily reinforced concrete shear wall such as the ultimate strength, ductility capacity and load-deflection hysteresis characteristics. Herein this paper, we discuss the experimental results obtained during a series of empirical studies. We examine in detail the effect of the size, location, shape and number of openings positioned within a wall panel on the variation of structural properties of a shear wall. We have summarized the results obtained from a set of significant data during the experimental studies as follows: 1. Location of an opening within a wall panel will determine a possible failure mode of the shear wall. When an opening is positioned at the bottom of a wall panel, the failure mode of the wall is a sliding shear failure at the bottom of the panel. When not, the failure mode is a compressive shear failure along the diagonal direction of the wall. 2. When an opening is positioned at the bottom of a wall panel, the observed ductility capacity is inferior to that obtained in a wall with an opening in the middle height of the wall. Based upon the empirical results, we propose an analytical formula to evaluate the shear strength of a wall having various types of openings within a wall panel, by use of which we can estimate the ultimate strength of a heavily reinforced concrete shear wall taking openings within a wall panel into consideration.