Most endocrinological syndromes in ovarian neoplasia reflect an overproduction of sex steroids, but the clinical manifestations do not correlate with the tumor histological subtypes. Most functional ovarian tumors are sex cord-stromal tumors and are usually of small to medium in size, but few are larger or giant. The size of the tumor does not correlate with the duration and the degree of clinical manifestations. Ovarian tumors of non-sex cord-stromal type may also be clinically functional. The immunohistochemical results suggests that alpha-inhibin and/or calretinin expression are useful markers in support of a diagnosis of sex cord-stromal tumor of the ovary. Although some of these tumors are AE1/AE3 positive, EMA negativity may be useful for the differential diagnosis with epithelial ovarian tumors.