The authors describe in this paper a Moroccan family presenting Alzheimer's disease. Among these 6 members, Mr M.K., 36 years old, was admitted in the University Psychiatric Department for 4 years of depressive syndrome, memory impairment and cognitive deficit. The transmission of Alzheimer's disease syndrome is autosomal dominant. The genetic studies showed a multifactorial determinism. For the familial cases with early onset, the mutation occurs on the amyloïd precursor protein and on the presenilin 1 and 2. The clinical course evoked a mutation of presenilin 1. The identification of such mutation in one of his sisters living in France confirmed the genetic transmission. The development of a curative treatment in Alzheimer's disease remains difficult. Selective inhibitors of cholinesterase can improve patients with mild to moderate Alzheimer's disease forms. In Morocco, only donepezil is available, but it is inaccessible for patients who need this treatment because of its high price. For Mr M.K., who still has a professional activity, symptomatic treatment, cognitive and psychological supports may allow him to maintain an adequate life for years.