Sir.—Hung et al in a recent issue of the Journal (134:25-27, 1980) advocated that a computerized tomography (CT) scan be done on any girl or boy with isosexual precocity without an obvious cause or in whom a CNS disorder is suspected. Root has reported that 85% of the cases of isosexual precocity in girls are idiopathic.1 Eberlein et al studied a series of 86 girls with sexual precocity, and found no cases due to a neurologic disorder.2 At Charlotte (NC) Memorial Hospital and Medical Center we have seen 77 girls with isosexual precocious development from 1974 through 1979. Only two of these girls had organic pathology—one with an ovarian cyst and one with hydrocephalus (Table). In the cases reported by Hung et al, one girl had hydrocephalus and another had seizures associated with sexual precocity. In both instances, a CT scan was indicated on neurologic considerations alone.