We report the case of a 28-year-old female followed for congenital dys
erythropoiesis type I which required repeated transfusions. Alpha-2a i
nterferon treatment was started because of post-transfusion chronic vi
ral hepatitis type C. Following this treatment, haemoglobin level incr
eased and reached normal value during the 24 weeks of interferon treat
ment, When interferon therapy was stopped, haemoglobin level returned
to previous values, requiring more transfusions, Resumption of interfe
ron therapy resulted again in a complete normalization of haemoglobin
level. Erythrokinetic studies demonstrated a striking reduction of the
ineffective erythropoiesis, and electron microscopy study a reduction
in nuclear structure abnormalities, To our knowledge, this is the fir
st report of the efficacy of interferon in congenital dyserythropoiesi
s.