Chromosomal analysis is routinely considered in all girls--but not boys-of short stature to screen for Turner syndrome. We report three patients of short stature (body height < 3rd percentile) with 45,X/46,XY mosaicism karyotype. They were brought to our outpatient department at the ages of 10, 13, and 18 years, respectively. Two of them had some stigmata of Turner syndrome. Two were treated with growth hormone. In the first patient, body height increased by 20 cm in 3 years 7 months. The second case increased by 6.5 cm in 8 months. We suggest that boys with unexplained short stature should be screened with chromosomal analysis, and growth hormone treatment should be offered to boys of short stature and 45,X/46,XY mosaicism before the epiphyseal plates close.