The winter wheat (variety Zitarka) field trials were set up in the autumn of 2002 and 2003 on silty loam stagnic luvisol at site Donji Miholjac in eastern Croatia. The soil was very acid (pHKCl = 3, 61) with low organic matter content (1, 56%), low P level (102 mg P2O5 kg- 1) and low K level (135 mg K2O kg-1). Treatments in the field trials were: 1. no fertilizer, 2. N1P1K1 (80:100:100), 3. N2P1K1 (120:100:100), 4. N2P2K2 (120:200:200), 5. N3P2K2 (160:200:200), 6. N4P2K2 (200:200:200) and 7. N5P2K2 (240:200:200). All those results, as well as results of total income (grain and straw yield × redemption price in 2003 and 2004 + subsidies) and costs were used for profit calculation and determining optimum fertilization ratio. Conducted experiment showed that fertilizer treatments effected yield, straw mass and production profitability. The grain yield increased from 2.94 t ha-1 (control plots) to 7.36 t ha-1 (200 kg N ha-1). The same tendency was approved in cost analysis. The share of fertilizer costs in total production costs were from 20.1 to 26.1% while the fertilizer cost amount per tone of achieved yield raised from 27.1 € for the lowest nitrogen fertilization rate (80 kg N ha- 1) to 35.2 € the highest fertilization rate (240 kg N ha-1). Obtained results indicated that the most profitable N levels are from 160 to 200 kg N ha-1.