A retrospective study was conducted on 45 children with congenital hypothyroidism (CH) to estimate the number of missed cases of CH among Omani children per year and compare the intellectual outcome of children diagnosed by neonatal screening (Group A) with those who were diagnosed clinically at a later age (Group B). Our results revealed 14 children in Group A, diagnosed at a mean age of 2.3 +/- 0.8 months and 31 children in Group B diagnosed at a mean age of 9.8 +/- 2.5 months. IQ assessment revealed that 67 per cent of the children in Group A had a normal IQ compared to only 15 per cent of those in Group B. The above results point to a great demand for a national screening programme in the Sultanate of Oman.