This study aimed to detect the age-specific mumps seroprevalence of an unvaccinated population of adolescents in Ankara, Turkey and to compare the prevaccination epidemiology of mumps with those of some other countries. Four hundred and forty adolescents (227 females, 213 males) aged 9-16 years who were admitted to the Adolescent Unit were included in this study. For each participant, a questionnaire was completed and mumps-specific IgG antibodies were screened quantitatively by enzyme-linked fluorescent assay. Of the 440 patients screened for mumps antibodies, 48 (10.9%) were seronegative. Mumps seronegativity according to sex and age groups were 13.6, 9.9, and 10.4% in females and 18, 10.2, and 6.2% in males in the age groups of 9-10, 11-13, and 14-16, respectively. Mumps immunization models similar to those of European countries might be acceptable for Turkey, but since a low vaccination coverage may shift mumps infection to older ages, mumps immunization of adolescents is important until a national mumps vaccination program with a high coverage could be sustained. The routine health supervision visit at ages 11 to 12 years is an ideal time to immunize unvaccinated adolescents.