Herniated intervertebral disc(HIVD) of the lumbar spine has been known to be relatively uncommon in the teenager and frequently be associated with trauma. However, with the changing life style and increasing sports activities, and most of all, with the advent of new imaging modalities, the incidence seems to be increasing gradually. In order to define the characteristic pattern of HIVD of teenager in the era of MRI, and to clarify the associated lesions, such as apophyseal ring fractures, authors performed this retrospective study in 55 teenager patients with HIVD(77 discs), in which MRI was used as main diagnostic modality. The following results were obtained 1) The incidence of the HIVD in teenager was 9.6%(55 patients) of total HIVD patients(575 patients) for 4 years from December 1989 to December 1993. 2) According to MRI findings, HIVD of the teenager could be classified into 3 distinct patterns; simple HIVD, lumbar apophyseal ring fracture(LARF), and vertebral rim lesion. 3) In simple HIVD, as for the MRI classification, protruded type was most frequent type and there was no sequestered type 4) In LARF, the incidence was 14.4% of teenager's HIVD and posterocephalad margin of L5 was the most common site of involvement. 5) Exophytic bony protrusion from the posterior margin of vertebral body, which we called vertebral rim lesion, could be defined on MR sagittal view in 6 cases.