In medicine, a chronic disease is a disease that is long-lasting or recurrent. The term chronic describes the course of the disease, or its rate of onset and development. A chronic course is distinguished from a recurrent course; recurrent diseases relapse repeatedly, with periods of remission in between. As an adjective, chronic can refer to a persistent and lasting medical condition. Chronicity is usually applied to a condition that lasts more than three months.

The definition of a disease or causative condition may depend on the disease being chronic, and the term chronic will often, but not always appear in the description:

• Chronic fatigue syndrome
• Chronic osteoarticular diseases: rheumatoid arthritis, osteoarthritis
• Chronic respiratory diseases: chronic obstructive pulmonary disease, asthma
• Chronic renal failure
• Diabetes mellitus
• Chronic Hepatitis
• Autoimmune diseases, like lupus erythematosus
• Cardiovascular diseases: heart failure, ischemic cardiomyopathy, cerebrovascular disease
• Neoplasic diseases not amenable to be cured
• Osteoporosis

Many chronic diseases require chronic care management for effective long-term treatment.

• Acute (medicine)
• Homeopathic theory of chronic diseases
• Chronic pain
• Course (medicine)
• Disease management (health)