Primary lymphoma presenting in the thyroid gland is uncommon. A review of the Yonsei University Medical Center experience between 1982 and 1994 was performed retrospectively to assess the treatment outcome and prognostic factors. There were four females and one male, and the median age was 65 years. All 5 cases presented with a neck mass. Two of them had co-existing biopsy-proved Hashimoto's thyroiditis and three cases were each in a hypothyroid state. All cases with non-Hodgkin's disease were of intermediate grade. One case was in stage IE and four were in stage IIE. Three cases were treated with surgery alone and two cases with bulky inoperable stage IIB were treated with chemo-radiotherapy. Chemotherapy induced a complete response in one and a partial response in the other with minimal transient toxicity. As the questions regarding justification for extensive surgical intervention increase, combined chemo-radiotherapy can be suggested as an initial treatment even in stage I, and stage II thyroid lymphoma based on prognostic factor evaluation.