16 cases of acute methotrexate (MTX) poisoning were reported to the Paris Poison Control Centre and 62 others were published between 1974 and 1995. Until 1992, MTX was mainly prescribed for neoplastic diseases. Clinical features involve acute renal failure, pancytopenia, and cutaneous or mucous injury. These cases emphasise major risk factors responsible for misuse and overdosage. Since 1992, MTX has been increasingly used in rheumatological or pulmonary diseases (rheumatoid arthritis, steroid-dependent asthma). Most of the overdosages were due to a medical misuse (in the dosage regimen or a misunderstanding of the prescription by nurse, pharmacist or patient). All patients had a bone marrow suppression. The treatment is based especially on early administration of folinic acid rescue.