Many patients have been characterized harboring a mutation in thyroid hormone receptor (TR) beta. Surprisingly none has yet been identified carrying a mutation in TRalpha1. To facilitate the identification of such patients, several animal models with a mutant TRalpha1 have been generated. While some phenotypic characteristics, such as an adult euthyroidism, are similar in the mutant mice, other aspects such as metabolism are quite variable. This review summarizes the most important consequences of a mutation in TRalpha1 in mice focusing on the TRalpha1-R384C mutation, and projects the insights from the animal models to a putative phenotype of patients with a mutated TRalpha1.