According the American Cancer Society about 120,000 new cases of melanoma in the US are diagnosed in a year. About 68,000 of these were invasive melanomas, with about 39,000 in males and 29,000 in women.

Melanoma is most often diagnosed in adults, although it can affect children and teenagers, too.
Prolonged exposure to ultraviolet sunlight or tanning beds, and a history of severe sunburn increase the chance of developing melanoma. Other risk factors include:

  • The presence and the number of atypical moles (also known as dysplastic nevi)
  • Personal diagnosis of melanoma or other form of skin cancer
  • Family history of skin cancer – two or more relatives diagnosed with skin cancer and melanoma
  • Fair skin, freckling or light hair Whites are 10 times likelier to develop melanoma than African Americans. Whites with red or blond hair, blue or green eyes, or fair skin that freckles or burns easily are at higher risk.
  • Red hair
  • Excessive ultraviolet (UV) light exposure, including from tanning beds; history of blistering sunburns especially during childhood
  • Age: Melanoma is most common in men over the age of 50 (more common than colon, prostate and lung cancer). Melanoma is the second most common cancer in teens and young adults and is the most common type of cancer for young adults.
  • A weakened immune system caused by AIDS, immunosuppressive drugs, or certain cancers
  • Other skin conditions such as xeroderma pigmentosum, a rare inherited condition in which the body cannot repair the DNA of skin cells damaged by UV radiation
  • A mutation in gene p53 that normally function as a tumor suppressor. When disabled, this gene can increase the likelihood of developing melanoma.
  • A mutation in the BRAF or "switch" gene that allows skin cells to keep growing and dividing. Greater understanding of this gene may lead to the development of new diagnostic tools and treatments for melanoma.
  • The CDKN2A (cyclin-dependent kinase inhibitor 2A) gene is also linked to melanoma though testing is usually done only in the context of clinical trials.