summary   Fragile X syndrome is, after Down's syndrome, the most common form of mental retardation. Women are potential carriers and can have the defective gene on one of their two X chromosomes without developing the complete syndrome. In this paper we examine which psychiatric disturbances may appear or develop in women because they are carriers of the fragile X mutation. Carriers have been found to have a higher frequency of anxiety disorders, affective disorders and schizotypal features.