Package substrates are provided. The package substrate may include a power line and a ground line on a first surface of a substrate body; a plurality of signal lines on the first surface between the power line and the ground line; and a lower ground pattern and a lower power pattern positioned on a second surface of the substrate body opposite to the first surface. The lower ground pattern may be disposed to be opposite to the power line and the lower power pattern may be disposed to be opposite to the ground line. Related semiconductor packages are also provided.