The clinical data of 91 patients with congenital hypothyroidism, not detected by neonatal screening, were reviewed. Our results disclosed that congenital hypothyroidism in Taiwan is more common in girls than boys, with a female to male ratio of 1.8:1. The majority of our patients were from a first pregnancy. Only 4.8% of our patients had a history of prolonged gestation, and the median value of birth weight in these patients was 3,300 g. Both of these data are comparable to those of the normal population. Short stature, constipation, dry skin and periorbital edema were the most common symptoms and signs. An ectopic thyroid gland was the most common type of congenital hypothyroidism in our series. The conditions of most of our patients were detected after the age of three months; poor mental prognosis was expected. However, it is hoped that neonatal screening programs for congenital hypothyroidism in Taiwan can improve such situations.