Picture this: You’re preparing dinner and open a fresh package of chicken breasts. As you’re getting ready to season them with rosemary and lemon, you notice something unexpected—a strange green discoloration deep inside the meat.

Finding green chicken can be alarming, and it’s natural to wonder whether it’s safe to eat. Before you throw the entire package away—or risk eating something questionable—it’s helpful to understand the science behind why chicken sometimes turns green.

The Four Most Common Reasons Chicken Turns Green

Food safety experts generally attribute green discoloration in chicken to one of four causes.

1. Green Muscle Disease (Deep Pectoral Myopathy)

This is the most common cause of green meat in modern commercial chickens. Also known as Deep Pectoral Myopathy (DPM) or Green Muscle Disease, it occurs in some fast-growing broiler chickens with unusually large breast muscles.

As the bird grows rapidly, the deep pectoral muscle may not receive enough blood and oxygen. Without adequate oxygen, the affected muscle tissue deteriorates and eventually turns green or grayish-green.

This condition develops while the bird is alive and may be triggered by vigorous wing movement or muscle swelling that restricts blood flow.

The important point: Green Muscle Disease is a muscle disorder—not a bacterial infection or foodborne illness. Although the affected meat has an unpleasant appearance and a tough, woody texture, it is generally not considered a food safety hazard.

2. Bruising or Broken Blood Vessels

Sometimes green or dark purple discoloration is simply the result of bruising. Birds can develop bruises during handling, transportation, or processing.

As the trapped blood breaks down, it changes color from purple to green, much like a healing bruise on human skin.

3. Bile Staining

If you’re preparing a whole chicken, you may notice a bright yellow-green stain near the body cavity.

This usually happens when the gallbladder is accidentally punctured during processing, allowing bile to leak onto the meat.

Although bile has an extremely bitter taste, it generally affects flavor rather than food safety. Trimming away the stained portion is usually sufficient if the rest of the chicken is fresh.

4. Spoilage and Bacterial Growth

This is the cause that requires the most caution.

Certain spoilage bacteria, including species of Pseudomonas, can produce a greenish or iridescent sheen on chicken. Unlike Green Muscle Disease, spoiled chicken is usually accompanied by several warning signs, including: