3 female patients who were being treated with methotrexate developed a non-Hodgkin lymphoma. The first patient, 67 years old, presented with an enlarged thyroid gland. The cytological punction was inconclusive and an open biopsy revealed a B cell non-Hodgkin lymphoma, which was localised. A week before the biopsy the methotrexate was discontinued. The patient herself reported that the swelling of her thyroid gland was diminished after cessation of methotrexate. The lymphoma showed a complete remission without chemotherapy being given. The second patient, a 78-year-old woman, developed a non-Hodgkin lymphoma in one of her tonsils that showed a partial remission after withdrawal of the methotrexate therapy. The third patient, a 66-year-old woman, presented herself with a pulmonary non-Hodgkin lymphoma. In this patient withdrawal of the methotrexate resulted in a complete remission of the non-Hodgkin lymphoma as well. Although no epidemiological study has shown an increased risk of lymphoproliferative disorders during the use of methotrexate, these spontaneous remissions suggest an aetiological link. If a non-Hodgkin lymphoma develops in a patient being treated with methotrexate then the therapy should be discontinued and chemotherapy should not be given straightaway.