The study esteemed the operational cost of production of conventional and transgenic soybean in Middle Paranapanema, São Paulo State, Brazil. Results of three experiments of regional evaluation were used with 19 varieties of soybean, being 17 conventional and 2 transgenic ones. The cost structures used were effective operational cost (EOC) and the total operational cost (TOC). The TOC, for hectare, of the transgenic soybean was 10,7% smaller than the one of the conventional soybean. However, the unitary cost for bag was smaller for the conventional soybean in reason of the productivity. The medium productivity was of 35,2 and of 31,3 bags for hectare for conventional and transgenic ones, respectively. The largest percemtile difference in TOC happened in the items "seeds " and "herbicide". The variation of the production cost for bag of the conventional soybean was from US$ 12.8 to US$ 18.3 and for the transgenic soybean US$ 13.7 and US$ 18.6. The high cost of the inputs committed the viability of the activity in the two production systems. There is need to continue the evaluation of the cultivation of transgenic soybean to know the most adapted ones in the area and to turn safer the technical indications.
Operational costs; conventional soybean; GM soybean
