Turner's syndrome (T.S.) is characterized for by a short stature, this becoming more evident during puberty and attainning a final height (FH) of aproximately 140 cm shorter than that predicted from analysis of mid-parental height for normal girls. A better FH increases life quality and self-esteem. Previous studies indicate that growth velocity (GV) is increased by Oxandrolone (O), growth hormone (GH) or both. O, increases GV and FH. 0.1 mg/kg/day of this drug rarely accelerates bone maturation. We investigated the effect of O on growth and bone maturation in patients with TS, by a double-blind study in 14 patients randomized into experimental (G1) and placebo (G2) groups. Enrollment criterias were kariotipic confirmation of TS; bone age>7 years; chronological age 8-14 years; normal TSH and T4; average intellectual skills no previous therapy with O, estrogens, anabolic agents or GH. G1 received O (0.1 mg/kg/day;Oxandrin. Gynex Pharm.) and G2 a placebo. They were controlled every 3 months, evaluating: height, weight, breast development, pubic hair and adverse effects. In months 0.6 and 12:BA, FSH, LH, E2, TSH, T4, IGF-1 (RIA), CBC, biochemical and lipid profiles were evaluated, G1 included 7 girls with a mean age of 11.05±1.68 years. height Z score=-3.8±1.2 and BA=9.9±0.97 years. without secondary sexual characters. G2 had CA=11.6±0.8 years, height Z score=-3.3±0.6 and BA=11.2±1.5 years; three patients with breast Tanner stage III. At baseline. G1: FSH=80.7±73 IU/L; LH=21.0±21.4 mIU/mL; E2<1.4 pg/mL; TSH=2.44±1.06 uUI/mL: T4=7.84=1.23 ug/dL; IGF-1=27.51±7.98 nmol/L. G2:FSH=89.14±109.5 IU/L;LH=29.4±47.8 mIU/mL: E2=3.0±3.2 pg/m/L;TSH=2.0+0.92 uUI/mL. T4=9.04±1.07 ug/dL;IGF. I=28.95±8.27 nmol/L. After 1 year of treatment GV was significative higher in G1 (6.97±1 cm) than in G2(4.74±0.96 cm): a BA/CA ratio changed significatively in G1(0.90±0.08 to 0.96±0.09± while no change occurred in G2(0.96±0.11 to 0.96±0.07). During 1 year of follow up O increases GV and BA significantly. O should be carefully evaluated as a single tnerapeutic agent in TS.