A 59-year-old man exhibited an enlarged right inguinal lymph node in February 2009. A pathological diagnosis of follicular lymphoma (FL), grade 3A, was made based on a biopsy specimen from the right inguinal lymph node. The immunophenotypes of the lymphoma cells were CD3-, CD5+, CD7-, CD10+, CD19+, CD20+, CD23+, IgM+, Igκ-, and Igλ+. Fluorescence-activated cell sorting (FACS) dual staining indicated that the cells were double-positive for both CD5 and CD20. Mantle cell lymphoma (MCL), small lymphocytic lymphoma (SLL) and CD5-positive diffuse large B-cell lymphoma (DLBCL) were ruled out by the presence of cyclin D1-, CD10+, and the pathological findings. Based on these findings, the patient was diagnosed as having CD5-positive FL. Eight cycles of rituximab plus six cycles of CHOP were performed, and complete remission was achieved. To our knowledge, this is a rare case of CD5-positive FL. A literature review suggested a relatively higher incidence in younger and male patients. Remarkably, patients with grade 3 tend to undergo a transformation from CD5-positive FL to DLBCL.