Due to the volatility of commodity prices, the application of the current cost theory in the evaluation of stocks is essential for providing information on the performance of agricultural cooperatives. The objective of this work was to check the economies and diseconomies in the stock cost of three commodities (soye, wheat and corn) in an agricultural cooperative in the state of Paraná. A descriptive and quantitative research was carried out, including a case study demonstrating the use of market quotas as an alternative to the evaluation of stocks according to information on current prices of agricultural commodities. The results show differences between the stock values appraised by the historic cost, the corrected historic cost, the current cost and the corrected current cost. Using the historic cost, no economy or diseconomy was observed. With the corrected historic cost there is a small economy of cost. However, using the current cost and the corrected current cost there is a considerable economy, which highlights the importance of the current cost theory. The application of the current cost theory in the evaluation of actives, when market information is available, is essential for obtaining satisfactory results because it increases the utility of the information provided.