Three patients with pure red cell aplasia, with or without co-existing large granular lymphocytic leukaemia, who remained transfusion-dependent despite treatment with established first-line therapy, were treated with low-dose subcutaneous alemtuzumab 15 mg twice to thrice per week, for 3 to 4 weeks. The mean response time was 17 days compared with a response time of at least 61 days on standard first-line therapy. There were no serious side-effects and the mean duration of remission was 13 months. Low-dose subcutaneous alemtuzumab is a safe and effective treatment for pure red cell aplasia and further trials should be conducted to compare the long-term effectiveness of this treatment with conventional therapy.