There are no known causes of lymphoma.

Certain viruses, such as the Epstein-Barr virus and the human immunodeficiency virus (HIV), can increase your chance of getting Hodgkin's or non-Hodgkin's lymphoma.  A weakened immune system and a family history of Hodgkin's or non-Hodgkin's lymphoma can also increase your chances of developing either lymphoma. 

Hodgkin's lymphoma is most likely to occur when a person is in his or her 20s or 30s. It is less common in middle age and becomes more common again after age 60.

Non-Hodgkin’s lymphoma is most likely to occur in people who are older than 60.