Congenital hypothyroidism (CH) is the most common cause of preventable intellectual disability in the pediatric population. Early diagnosis and treatment during the first month of life are essential to avoid delaying the neuropsychological development of these patients. Objective: to describe the social, cognitive, and psychomotor development of children with CH treated at the National Institute of Child Health (INSN) in Lima, Peru. Patients and Method: Retrospective analysis of 26 CH patients seen during 2012-2017 at INSN were reviewed. The aspects of neuropsychological development studied were: cognitive development (IQ), social development (social category), and psychomotor development (gait, speech, and chest control). The IQ was classified according to the result of the Weschler IV scale. An analysis was carried out with the Fisher-Freeman-Halton test to verify if there was a difference in the frequency of the variables according to the age of diagnosis and beginning of treatment. Results: Most of the patients presented a borderline IQ (38.5%), the most frequent social category was educable (88.7%), and most of the patients presented delay in developing the speech (88.5%). In the Fisher-Freeman-Halton test, there was only a statistically significant increase in the number of cases of speech delay in patients treated between 22 days and 12 months of age (c2 = 11.246, p = 0.002, V of Cramer = 0.778). Conclusion: Neuropsychological developmental delay was more frequent in patients with CH diagnosed and treated after 21 days of age.