Ninety‐eight consecutive patients with myelodysplastic syndrome were randomized to a treated or a control group, both receiving conventional supportive therapy. The treated group were given 13‐cis‐retinoic acid 20 mg/d if marrow blasts were ≦ 5% or cytosine arabinoside 10 mg/d subcutaneously on 6 d /week if marrow blasts were 6‐30%, to which retinoic acid was added after 12 weeks. Serum levels of the drugs in the treated group were similar to those that would produce inhibition of CFU‐GM growth in vitro. In patients in the low blast group receiving retinoic acid. myeloid surface antigens reverted from an abnormal to a normal pattern.

A randomised therapeutic trial of 13-cisretinoic acid was carried out in 70 patients with myelodysplastic syndrome having 5% or fewer marrow blast cells. Among non-sideroblastic patients the 1-year survival in the treated group was 77%, compared with 36% in the control group. There were too few deaths among patients with sideroblastic anaemia to allow any effect of therapy on survival to be evaluated.