Introduction. Cadmium is a metal that has been found in milks and, therefore, represents a big risk for human health. Biosensors have been used as tools for the rapid determination of this kind of compounds in several matrices. Materials and methods. An amperometric biosensor and screen printed electrodes were used to immobilize the urease enzyme, by the use of the cross linking method. The subtract used for the determination was urea. Before determining the cadmium concentration in the milk, the method used was validated by making calibration curves and evaluating the repeatability of both the method and the instrument. Results and discussion. The linear rank for the method was 5 mM to 60 mM with a high correlation between variables. The quantifica tion limit of the method was 0.05 mg/L. The variation