The Hunter Outcome Survey (HOS), an international, long-term observational registry of patients with Hunter syndrome, was used to develop a simple mnemonic screening tool (HUNTER) to aid in the diagnosis of Hunter syndrome. Data regarding the prediagnosis prevalence of ten specific signs and symptoms present in individual patients enrolled in the HOS were used to develop the HUNTER mnemonic screening tool. A total score of 6 or greater using a weighting scheme in which certain manifestations were assigned a weight of 2 (facial dysmorphism, nasal obstruction or rhinorrhea, enlarged tongue, enlarged liver, enlarged spleen, joint stiffness) and others assigned a weight of 1 (hernia, hearing impairment, enlarged tonsils, airway obstruction or sleep apnea) correctly identified 95 % of patients who had no family history of Hunter syndrome or who were not diagnosed prenatally. No association between age at diagnosis and HUNTER score was found. Conclusion: The HUNTER mnemonic appears to be a useful screening tool. Further validation in the clinical setting will be necessary to confirm its utility.