INTRODUCTION: The congenital erythropoietic porphyria (Günther's disease) (CEP) is a rare autosomal recessively metabolic disease due to the deficit of uroporphyrinogen III cosynthetase, fourth enzyme of the porphyrin-heme biosynthesis. This disease is characterized by severe cutaneous photosensitivity with profound skin lesions, hemolytic anemia and excess of uroporphyrin I excretion. The vital prognosis is very bad and until now, no treatment seems to be efficient. Bone marrow transplantation seems to be able to correct the enzymatic deficit that causes the disease because it is located in the bone marrow. OBSERVATION: We report the case of a four and a half year old girl who received an allogeneic bone marrow transplantation (BMT) at the age of two. Despite an encouraging result, the first transplantation failed. A second allogeneic transplantation was attempted eight months later with the same HLA identical heterozygous donor and bone marrow engrafment succeeded. Twenty one months after the second bone marrow transplantation, clinical and biological results are still excellent. DISCUSSION: No classical treatment of CEP really proved its efficiency and no one was curative. CEP resulting from an homozygous deficiency in uroporphyrinogen III cosynthetase, enzyme that takes part in the porphyrin-heme biosynthesis which is principally located in the erythropoietic system of the bone marrow, substitution of this defective lineage by BMT was a very attractive treatment to correct this anomaly. The first bone marrow transplantation attempted on an affected child in 1990 in Manchester failed because the patient died of infections complications. After the failure of the first transplantation, our little patient is now healed twenty one months after the second BMT and biochemical anomalies are corrected. If a long follow up is necessary to appreciate the long-term efficiency of this treatment, allogenic bone marrow transplantation seems to cure Günther's disease and must be proposed as the treatment of this affection.