Eosinophilia and tissue infiltration by eosinophils are frequent findings in Hodgkin lymphoma, but they are extremely rare in B-cell lymphoma. Reported herein is a case of follicular lymphoma with extensive lymph node infiltration by eosinophils. The patient was a 71-year-old woman who had a mass in the vicinity of the pancreas found on routine ultrasonography. Subsequent CT indicated several enlarged abdominal lymph nodes, although superficial lymph nodes were not palpable. Two swollen mesenteric lymph nodes were excised to determine the cause of the lymphadenopathy. Histology indicated extensive infiltration of numerous eosinophils to the interfollicular area, especially in the dilated sinuses. The lymphoid follicles were relatively small, had inconspicuous germinal centers, and were scattered between dilated sinuses. Based on the histology, immunohistochemistry, and chromosomal abnormality, a diagnosis of follicular lymphoma was made. Expression of interleukin-3 (IL-3), IL-5, eotaxin, eotaxin-2, and eotaxin-3 was investigated on reverse transcription-polymerase chain reaction of the lymph node tissue, but none of the mRNA expression levels were elevated. This was a unique case of follicular lymphoma with extensive eosinophil infiltration, and to the best of the authors' knowledge this is the first such case ever reported.