In his article, the author presents the issues related to the analysis of effectiveness of marketing research in firms, paying particular attention to the need of implementation and carrying out within organisation the economic analysis and control of resources spent on this sphere of enterprise's activities. He discussed the subject matter of measurement of effectiveness of marketing research, the degree of variability of research expenses incurred by the firm, ways of computation of the level of effectiveness and the measures used in the process of analysis of effectiveness as well as functions of the statistical analysis and methods of the optimum allocation of funds on research in marketing budget and a general model of investment in marketing research and the most often made by managers measurement errors.