Process for monitoring backlash in a gear of a joint of an industrial robot, wherein said joint comprises: a first joint body and a second joint body coupled together with the possibility of moving with respect to one other, a motor provided with an encoder, and a motion-transmission assembly (53, 55) designed to transmit the torque generated by said motor to said second joint body to bring about a movement of said second joint body with respect to said first joint body, said transmission assembly (53, 55) comprising said gear, said process comprising the steps of: - driving via said motor a movement of said second joint body with respect to said first joint body; wherein driving said movement of said second joint body includes driving said movement according to a test mode in which the velocity of movement is constant and in which the toothed wheels of said gear are arranged with their own axes of rotation oriented horizontally so that the force of gravity can contribute to induce impact between the teeth of the toothed wheels of the gear; - during said movement, acquiring a signal of said encoder; - receiving a characteristic oscillation curve, said characteristic oscillation curve being a damped-oscillation curve; - processing said signal for identifying an oscillation curve in said signal, corresponding to said characteristic oscillation curve and reflecting the mechanical vibrations generated by the impact between the teeth of the toothed wheels of the gear; - determining a parameter of the oscillation curve identified, indicating the maximum amplitude of the oscillation curve identified; and - determining a condition of backlash on the basis of said parameter determined. said process comprising the steps of: - driving via said motor a movement of said second joint body with respect to said first joint body; - driving via said motor a movement of said second joint body with respect to said first joint body; wherein driving said movement of said second joint body includes driving said movement according to a test mode in which the velocity of movement is constant and in which the toothed wheels of said gear are arranged with their own axes of rotation oriented horizontally so that the force of gravity can contribute to induce impact between the teeth of the toothed wheels of the gear; - during said movement, acquiring a signal of said encoder; - receiving a characteristic oscillation curve, said characteristic oscillation curve being a damped-oscillation curve; - processing said signal for identifying an oscillation curve in said signal, corresponding to said characteristic oscillation curve and reflecting the mechanical vibrations generated by the impact between the teeth of the toothed wheels of the gear; - determining a parameter of the oscillation curve identified, indicating the maximum amplitude of the oscillation curve identified; and - determining a condition of backlash on the basis of said parameter determined. - during said movement, acquiring a signal of said encoder; - receiving a characteristic oscillation curve, said characteristic oscillation curve being a damped-oscillation curve; - processing said signal for identifying an oscillation curve in said signal, corresponding to said characteristic oscillation curve and reflecting the mechanical vibrations generated by the impact between the teeth of the toothed wheels of the gear; - determining a parameter of the oscillation curve identified, indicating the maximum amplitude of the oscillation curve identified; and - determining a condition of backlash on the basis of said parameter determined.