Onychomadesis is the proximal separation of the nail plate from the nail matrix due to a temporary cessation of nail growth. It can occur in children of all ages including neonates. Diagnosis is made clinically through palpation and inspection of the nail plate. Physicians should consider underlying associations. A review of the patient's history for any viral illnesses 1 to 2 months prior to nail changes often will help identify the causative disease. Onychomadesis typically is mild and self-limited. There is no specific treatment, but a conservative approach to management is recommended with treatment of any underlying causes and supportive care. Spontaneous nail regrowth usually occurs within 12 weeks and may occur faster in children. In this article, causes of onychomadesis are described, including the connection between hand-foot-and-mouth disease (HFMD) and onychomadesis. We also explore several theories of possible mechanisms for onychomadesis; however, the precise mechanism remains unclear and further investigation is needed.