Introduction. - X-linked adrenoleukodystrophy (ALD) is the most frequent type of leukodystrophy (1/17 000 males). The phenotypic range in male patients varies from the severe cerebral presentations in children to the milder myeloneuropathy and to isolate adrenal insufficiency. More than a half of the carrier females display clinical symptoms over the age of 40 years. Observation. - Diagnosis of ALD was raised in a 40 year-old female who presented with spastic paraparesis and sphincterian dysfunction, occurring after the delivery of her first child. There was no family history of ALD. Very long-chain fatty acids (VLCFA) were assayed in her one-year-old son in order to propose appropriate hormonal and neurological survey. His dosage was abnormal and an adrenal insufficiency was subsequently found. A brain MRI will be proposed biannually when he reaches to age of for years. The proband’s mother had an increased level of VLCFA, showing that she was a carrier. Family screening was extended to the proband’s sisters and maternal aunt who already had children, but also to her brother, who may express a mild form of the disease later on, and to her maternal uncles who might be asymptomatic carriers. A frameshift mutation was found in the ABCD1 gene and will allow accurate carrier identification and prenatal diagnosis in the family. Conclusion. - ALD diagnosis should be evoked in a woman affected by myelopathy despite the lack of family history. Such a diagnosis has severe consequences since some of the related males may carry the mutation although they do not display any symptom at time of diagnosis, and because carrier females have a risk to both have a clinical expression of the disease and give birth to an affected boy. Introduction to X-linked adrenoleukodystrophy (ALD) is the most frequent type of leukodystrophy (1/17 000 males). The phenotypic range in male patients varies from the severe cerebral presentations in children to the milder myeloneuropathy and to isolate adrenal insufficiency. More Observation. ALD was raised in a 40 year-old female who presented with spastic paraparesis and sphincterian dysfunction, occurring after the delivery of her first child. There was no family history of ALD. Very long-chain fatty acids (VLCFA) were assayed in her one-year-old son in order to propose appropriate hormonal and neurological survey. A His dosage was abnormal and an adrenal insufficiency was found after. A brain MRI will be proposed biannually when he reaches to age of for years. The proband’s mother had an increased level of VLCFA, showing that she was a carrier. to the proband sisters and maternal aunt who already had children, but also to her brother, who may express a mild form of the disease later on, and to her maternal uncles who might be asymptomatic carriers. A frameshift mutation was found in the ABCD1 gene and will allow accurate carrier identification and prenatal diagnosis in the family. Conclusion. ALD diagnosis should be evoked in a woman affected by myelopathy despite the lack of family history. Such a diagnosis has severe consequences since some of the related males may carry the mutation although they do not display any symptom at time of diagnosis, and because carrier females have a risk to both have a clinical expression of the disease and give birth to an affected boy.