Ten patients with the myelodysplastic syndrome (eight with anemia, two with granulocytopenia, four with thrombocytopenia) were given etretinate (ER) and retinoid acid (RA). No correlation was seen between the RA effect in vitro and its clinical effect. No effect was seen of the ER-treatment or of the RA-treatment on anemia, thrombocytopenia or the abnormal karyotype seen in three patients. In three of eight patients given RA a decreased blast cell percentage in the bone marrow was seen, and in two of these there was also a normalization of the in vitro bone marrow cell colony formation. We found no clinical effect of ER and only a minimal one of RA.