The purpose of this study is an attempt to explore the impact of various market structure elements (R&D, Advertising, Capital Intensity, Inventory Turnover, and Firm Size)on the financial accounting performance measurements in the United States pharmaceutical industry. Firms will be selected and analyzed based on two criteria; those who's major manufacturing operations is pharmaceuticals and those whos manufacturing operation may include pharmaceuticals, but they represent only a section of the firm manufacturing operations. This includes approximately 332 publicly traded United States firms. The study findings indicate that firm size and R&D intensity are associated significantly and positively with ROA and RE, where advertising intensity and capital intensity are significantly and positively associated with ROE only in the pharmaceutical industry. However, Inventory turnover is not statistically significant for both ROA and ROE and cannot be used to determine the financial performance of US pharmaceutical firms.