Non-Hodgkin's lymphoma is the fifth most common cancer in the United States, accounting for about 4% of all malignancies in both men and women. The disease comprises a variety of cancers of the lymphatic system exclusive of Hodgkin's lymphoma. B-cell lymphomas represent most cases of non-Hodgkin's lymphoma, and T-cell lymphomas account for the rest. Due to the myriad types of non-Hodgkin's lymphoma, classification often proves difficult for healthcare professionals. Exams and tests can help to identify the presence or absence of the disease and aid in classifying the lymphoma. Adults make up the majority of cases of non-Hodgkin's lymphoma. The incidence has increased by nearly 2-fold over the past few decades, with AIDS-related lymphoma accounting for some of this growth. Non-Hodgkin's lymphoma is seen more commonly in certain populations, such as elderly individuals, men, and whites. Children often present with different types of the disease. Recent advances in treatment, including chemotherapy, radiotherapy, and immunotherapy, have shown promise in combating this disease.