PURPOSE: To describe the MRI and CT findings of temporal bone Langerhans cell histiocytosis. MATERIALS AND METHODS: The MRI (n=8) and CT (n=7) findings of nine lesions of temporal bone Langerhans cell histiocytosis in six children were retrospectively reviewed. Eight lesions were pathologically confirmed and one was clinically diagnosed. The findings were analyzed for bilaterality, location, lesion extent, signal intensity, the attenuation of soft tissue lesions seen at MRI or precontrast CT, enhancement pattern at MRI or CT, and the pattern of bony destruction at CT. RESULTS: Bilateral involvement was present in three of six patients (50%). Lesions were most frequently located in the mastoid (n=8, 89%), followed by the petrous ridge (n=6, 67%), and the squamous portion (n=3, 33%). Seven (78%) lesions extended to the ipsilateral cavernous sinus (n=3), sphenoid bone (n=3), orbit (n=2), or epidural space (n=2). The signals of the soft tissue lesions were isointense in five cases (63%) on T1-weighted images and hyperintense in six (75%) on T2-weighted images. Five lesions (71%) were isodense on precontrast CT scans. The enhancement patterns were inhomogeneous in six cases (75%) at MRI, and homogeneous in five (71%) at CT. All lesions demonstrated bony destruction without periosteal reaction and five (71%) showed ill-defined destruction, with crossing sutures. CONCLUSION: Familiarity with findings of predominant mastoid involvement, isointense or isodense soft tissue lesions seen on T1-weighted images or at precontrast CT, with relatively homogeneous enhancement at CT, and irregular bony destruction with crossing sutures may be helpful in narrowing the diagnosis of temporal bone Langerhans cell histiocytosis.