Choice of sex in children with ambiguous genitalia requires morphological evaluation of external and internal genitalia together with prevision of the kind of pubertal and psychosexual development. Female features in female pseudohermaphroditism, ambiguous in true hermaphroditism and mixed gonadal dysgenesis, male, ambiguous or female in male pseudohermaphroditism, are usually awaited. Increased risk of malignancy in poorly differentiated male gonads should be considered. In neonates diagnostic procedures should be urgently undertaken in order to choose correct sex as soon as possible. Parents must be convinced from the beginning in order to remove any possible doubt. There should be no change in sex, as a rule, after the second year of life, unless a strong psychosexuality arises in definite opposition to the sex so far assumed. In our experience, in 4 out of 23 cases with ambiguous genitalia, neonatal choice of female sex was refused by parents.