Grisel's syndrome is a non-traumatic subluxation of the atlantoaxial joint following an inflammatory process in the upper respiratory tract. Patients with Down syndrome have higher risks of developing atlantoaxial instability. This issue is mainly due to low muscle tone, loose ligaments, and alterations to the bone in patients with Down syndrome. Accompaniment of Grisel's syndrome and Down syndrome was not perused in recent investigations. To our knowledge, only one case of Grisel's syndrome in an adult patient with Down syndrome has been reported. In this study, we present a case of Grisel syndrome in a 7-year-old boy with Down syndrome following lymphadenitis. A 7-year-old boy with Down syndrome was admitted to the orthopedic ward of Shariati hospital with a possible diagnosis of Grisel's syndrome and treated with mento-occipital traction for ten days. In this case report, we represent a child with Down syndrome with Grisel's syndrome for the first time. We also imitated a simple and applicable non-surgical treatment for Grisel's syndrome.