Untreated hypothyroidism in children usually results in delayed puberty, but juvenile hypothyroidism causes isosexual precocious puberty in a rare syndrome called Van Wyk Grumbach syndrome, with a complete reversal to the pre pubertal state following thyroid hormone replacement therapy. We report here, a 7-year-old girl who presented with short stature, constipation and isosexual precocious puberty due to the long standing untreated severe hypothyroidism with this syndrome.