Congenital hypothyroidism (CH) is the most important cause of preventable mental retardation. The prevalence of CH varies by geographic region, race and ethnicity. In the countries of the Northern hemisphere, the prevalence has been reported as 1:4,000 live newborns. The prevalence is remarkably different among the countries of Latin America not only because of their different races and ethnicities but also because of the heterogeneous social-economic development. The prevalence of CH in 1984 in Peru was reported as 1:1250. In 2007, the reported incidence by the Instituto Nacional Materno Perinatal was 1:1638. A recent retrospective study performed by the Instituto Nacional de Salud del Niño in Lima, Peru described the average age of diagnosis of CH as 5,9 months +/- 5,28. This late age of CH diagnosis certainly suggests the poor efficiency of the current neonatal CH screening programs in Peru. Every Peruvian infant deserves a timely newborn screening and treatment for CH. The Peruvian government is responsible for ensuring this mandatory goal is achieved promptly.