honey is a known product for its nutritional value. considering that offer is smaller than the market demand, honey is relatively expensive. this fact contribute to the incentive of its adulteration by commercial sugars derived from sugar cane and corn. as these plants have a distinct stable carbon isotope composition than plants commonly used by bees as sources of nectar, it is possible to use the stable carbon isotope composition of honey to detect addition of commercial sugar cane and corn sugars. in this study we analyzed samples of c3 plants commonly used by bees, subproducts of c4 plants, and 61 samples of honey. the d13c of c3 plants values had on average of -28.9±1.1？ (n=8), while the commercial sugars had an average value of -11.1±0.7？ (n=3). approximately 8% (5 samples) of the 61 samples analyzed had d13c values that clearly indicated the addition of commercial sugars (adulteration). the sample number 5 had a d13c valor equal to -12.9？, indicating that it was all made of commercial sugars. the samples numbers 13, 14, 33, and 54 had values equal to -21.0, -19.9, -21.9 and -17.6？, respectively. these values also indicated the addition of commercial sugars. the methodology used in this study proved to be a valuable and simple complement to the conventional chemical and physical methods normally used to detect honey adulteration.