Semiconductor devices are provided. The semiconductor device includes a control signal generator and a first data input unit. The control signal generator generates an inverted control signal including a first bit and a second bit using a decoded signal in response to a test enable signal. The first data input unit inverts a first bit of input data in response to the first bit of the inverted control signal to generate a first bit of first internal data. Further, the first data input unit inverts a second bit of the input data in response to the second bit of the inverted control signal to generate a second bit of the first internal data.