Aiming to contribute for the implementation of Precision Agriculture in sugar cane crop in the Brazilian, the main objective of this research was to generate a yield map of this culture. In order to do that this project involved the design and test of a sugar cane yield monitoring system during 2003 and 2004-harvest seasons. The system was mounted on a CASE 7700 1999 sugar cane combine, and consisted of a scale, a data acquisition system, and a GPS. The scale consisted of a weigh plate supported by load cells. The load cells were supported by a protective box mounted in the frame of the harvester elevator. The scale, which was mounted in the floor of the elevator, directly recorded instantaneous measurements of the sugar cane yield. In order to evaluate the accuracy of the system, later each loaded truck was weighted on an electronic platform scale upon arrival at the sugarcane mill. The weight of each truck was used as the standard. For each test, the scale readings were totaled and compared to the actual yield, which was measured by the weight of each truck. The scale’s average percent error was 0.96 % and the maximum error was 6.4%. A sugar cane yield map was generated in a 43 ha area plot of a sugar plantation, located in Araras, Sao Paulo State, Brazil. The results show that the yield variability in this area is significant.