Information from the 1988 National Health Interview Survey Medical Device Implant Supplement was used to obtain the first population estimates of the prevalence of implanted tympanostomy tubes, a common treatment for otitis media. The prevalence rate was estimated to be 13 per 1000 children aged younger than 18 years. Statistically significant differences in prevalence were found for sex (boys, 15/1000; girls, 10/1000), race (Whites, 15/1000; others, 4/1000), and activity level ("limited," 44/1000; others, 11/1000). Thirty percent of the tubes were replacements; infection was the reason for 75% of the original implants. The morbidity and costs associated with tympanostomy tubes are of public health importance.