Background: Among hormone deficiency, hypothyroidism is considered to be the most common disease, and is subdivided into congenital or acquired, based on the onset. The exact site of dysfunction can further classify the disease into primary and secondary. It is crucial to determine the level of severity of the disease as severe cases may end up in a coma. On the other hand, mild cases may be asymptomatic. Diagnosis is mainly based on serum thyroid hormones levels, and the treatment depends on thyroxine administration with an excellent prognosis. Aim of this review: was to explore the types of hypothyroidism, its diagnosis, and study the best course of management that must be followed. Methodology: We conducted this review using a comprehensive search of MEDLINE, PubMed, and EMBASE, January 1985, through February 2017. The following search terms were used: hypothyroidism, myxedema, classification of thyroid diseases, investigation of hypothyroidism, management of hypothyroidism. Conclusion: Hypothyroidism is a common disease that usually affects females more than males. Populations at higher risk include, old women, pregnant women, dyslipidemic patients, and patients with a history of radiation exposure. Diagnosis is based on measurement of TSH along with the thyroid hormone levels. Management includes administration of thyroxine and must be done early.