Androgens are considered the treatment of choice for the anaemia of myelofibrosis with myeloid metaplasia (MMM). Good results have been reported in a few patients treated with danazol, a synthetic attenuated androgen. The long-term efficacy and tolerability of danazol as treatment for the anaemia of MMM was evaluated in 30 patients, who received 600 mg/d, with progressive tapering to the minimum effective dose in the responders after 6 months. Complete response (CR) was defined as transfusion cessation with normal Hb and partial response (PR) as an Hb increase ≥1·5 g/dl with transfusion-independent Hb values >10 g/dl maintained for at least 8 weeks. Median follow-up was 20·5 months (range: 3·5–58 months). Response was achieved in 11 patients (37%), including eight CRs and three PRs. Median time to response was 5 months (range: 1–9 months). Four patients stopped responding at 6–24 months, two responders discontinued treatment because of toxicity, and five maintained response at 3·5–42 months. Pretreatment variables associated with response were lack of transfusion requirement (P= 0·001) and higher Hb at treatment start (P= 0·02). Toxicity was usually moderate, leading to treatment withdrawal in only two cases. Danazol is effective and well tolerated in a substantial proportion of MMM patients with anaemia.