The issues of the profitability of equity constitutes an important aspect in the enterprise management, particularly as an element which can increase market value. Against this background the realistic estimate of the return on equity and its impact on the effectiveness of the enterprise come into a relevant prominence. The main aim of the article is to draw attention to the variety of assessment methods return on equity, existing in the literature on the subject. This paper shows the results of theoretical and empirical research on the comparative analysis of rates of return on equity, based on the net profit, comprehensive income, cumulative retained earnings and cash flows. The adoption of a particular method of estimating the return on equity may differentiate assessment of the effectiveness of the enterprise. The empirical studies have been included in selected fuel industry companies quoted in the Warsaw Stock Exchange in the period 2009–2011.