Objectives: Acute otitis media (AOM) commonly affects young children and occasionally results in serious complications/sequelae. This pilot cost-of-illness study aimed to assess the economic burden of long-term AOM complications/sequelae in Belgium, and to establish a thorough methodology for a larger study. Methodology: We retrospectively reviewed charts of patients aged 10-20 years with long-term complications/sequelae considered to be AOM-related, and >= 8 years of follow-up. From a list of 215 eligible patients, we selected 25 patients representing each of seven categories of complications/sequelae. Results: Included patients had a mean age of 12.9 years; nine had chronic suppurative otitis media with cholesteatoma; six sensorineural hearing loss; six chronic perforation of the tympanic membrane; and one each with conductive hearing loss, facial paralysis, neurological impairment after intracranial complications, and complications of surgery. During 8-15 years of follow-up, the most common complications were hearing loss, chronic otitis media (OM), and cholesteatoma. These generally occurred >5 years after the first AOM event, although chronic OM occurred after a mean time of 3.3 years. Yearly public health care payer (PHCP) costs ranged from (sic) 119 to (sic) 7957 per patient, and were highest for patients with sensorineural hearing loss. Yearly costs to the patients ranged from (sic) 7 to (sic) 289 per patient, and were also highest for patients with sensorineural hearing loss. Conclusions: Although complications/sequelae of AOM are rare, they can result in substantial costs. The applied methodology should be feasible for a larger study, with some minor adjustments.