Retinoids are derivates of vitamin A. They play an imortant role in em
bryogenesis and differentiation of normal cells. All-trans retinoic ac
id (ATRA, Tretinoin) and 13-cis retinoid acid (cRA, Isotretinoin) are
the most important isomers. The first treatment with retinoids in a pa
tient with an acute promyelocytic leukemia (APL) is reported in 1983.
Since 1988 studies are done investigating the effect of retinoids in A
PL. These studies demonstrate, that retinoids can achieve a high remis
sion rate in patients with APL but without curing pa tients. A combina
tion with chemotherapy is always necessary. The main advantage of usin
g retinoids in this disease is a rapid improvement of the hemostatic d
isorder and the absence of an aplastic phase. Side effects of retinoid
s are those of the hypervitaminosis A syndrome and have to be consider
ed in every patient treated with this durg. The addition of alpha-Toco
pherol seems to ameliorate the toxicity of retinoic acid (RA). The the
oretical background of the treatment with retinoids in APL as well as
the clinical studies done so far are explained in detail.