Just about any color of shirt goes well with gray pants. Gray is a simple neutral color that is extremely versatile and blends well with other colors, especially when the gray has undertones of blue. Gray pants are an especially good choice to wear with bright colors, as they tend to tone down the effect of a vivid color.
Jewel tones also work well with gray, especially deep purple, burgundy, ruby, emerald green or plum. A gray that isn't weighted heavily toward blue or yellow in its undertones works well with unexpected colors such as orange, pale blue, mustard yellow or even bright pink.
Gray also goes well with other neutrals. Combinations of gray and brown look sophisticated and understated, and gray and black together also look sophisticated. Gray pants can even be worn well with a simple white t-shirt or white dress shirt, depending on the style of pants. Several shades of gray can also be worn successfully together to create a calming, monochromatic statement. This look can be particularly slimming. When wearing all gray, any tiny pop of color, for instance from a tie or scarf, makes a big impression. Gray pants can be worn with almost any shoe color and are a neutral clothing item that goes well with brown shoes.