Multiple myeloma is more common in men than women, and more common in African Americans than in those of other backgrounds. The median age at the time of diagnosis is 63 years old.

Most people with multiple myeloma do not have clearly identifiable risk factors. The disease rarely affects more than one person in a family. Immediate family members have a slightly increased risk of developing a similar condition.

There is some evidence that certain chemicals can slightly increase the risk of multiple myeloma. For example, there are slightly higher rates of the disease in agricultural workers exposed to pesticides and fertilizers, petrochemical and sheet metal workers, and those exposed to wood dust or fuel oil products.