Have you ever opened a package of chicken and noticed a strange green, yellow-green, or gray-green patch inside the meat? It can look alarming, but one possible explanation is a condition called **deep pectoral myopathy**, commonly known as “green muscle disease.” It affects a specific muscle deep inside the chicken breast and can occur when the muscle does not receive enough blood and oxygen. As the damaged tissue changes, it can develop a noticeable green color. The chicken may otherwise look completely normal from the outside.

This condition is more commonly associated with modern broiler chickens, which are bred to develop large breast muscles. During sudden or vigorous wing movement, the muscles can swell, and pressure in the surrounding area may reduce blood circulation. The resulting lack of oxygen can damage the deep pectoral muscle and eventually cause the green discoloration. “The chicken may look perfectly normal on the outside,” even when a green section is visible after cutting into the breast.

However, not every green-looking piece of chicken is caused by green muscle disease. Spoilage can also cause unusual color changes, especially when combined with a strong unpleasant odor, slimy or sticky texture, widespread discoloration, damaged packaging, or improper storage. Fresh chicken can naturally vary from pale pink to darker shades, so color by itself is not enough to determine whether it is safe.

If you find a clearly localized green section inside an otherwise normal chicken breast, it may be muscle damage. The affected portion should not be eaten. If you notice additional signs of spoilage or are unsure about the cause, the safest choice is to discard the chicken rather than take a risk.

When cooking chicken, don’t rely on color alone to judge whether it is safe. Use a food thermometer and make sure the thickest part reaches **165°F (74°C)**. Proper refrigeration, safe handling, and thorough cooking are important whenever dealing with raw poultry.