During the last 4 decades of XXth century, non Hodgkin lymphomas (NHL) have increased dramatically until reaching the 7th place among cancer. During the same period, > Hodgkin lymphoma (HL) remained stable. We described here epidemiological characteristics of different entities of NHL and of HL. To explain this increase, a large number of risk factors have been studied. In addition to infectious agents, genetic polymorphisms are one of the most new actors of the multifactorial process of lymphomagenesis.