A 62-year-old Japanese woman was diagnosed as having follicular lymphoma (FL, grade 3, CS IIIA, IPI high-intermediate risk) in May 1998. After eight courses of CHOP therapy, she achieved a complete remission (CR). In November 1998, her FL relapsed, and she achieved a second CR after two courses of MINE therapy. High-dose etoposide was used for autologous peripheral stem cell mobilization. In May 1999, she underwent high-dose chemotherapy with autologous peripheral blood stem cell transplantation (auto-PBSCT). Four months after the auto-PBSCT, bilateral cervical lymphadenopathy developed. Histopathological findings from a biopsied cervical lymph node showed angioimmunoblastic T-cell lymphoma (AILT). The patient was treated with modified CVP therapy, and she is alive with no evidence of lymphoma five years after auto-PBSCT. Clinical and histopathological findings showed that the FL and AILT in this case were not concomitant. It is thought that in this case, the AILT developed as a post-transplant lymphoproliferative disorder after auto-PBSCT for the FL.