We describe a patient with systemic lupus erythematosus and severe, treatment-resistant thrombocytopenia. Prolonged treatment with high-dose steroids eventually led to reversal of the thrombocytopenia, but the dosage could not be tapered without relapse. Low-dose intravenous bolus cyclophosphamide was given, producing a response within 1 week. The steroid dosage was tapered, without relapse. Other than reversible alopecia, no toxicity was seen. The use of this treatment should be considered in patients in whom more conventional therapies are not effective or cannot be tolerated.