목적: Horizontal semicircular canal (HSC) BPPV accounts for approximately 10% to 20% of all patients presenting with BPPV. Generally it is diagnosed by the head roll test (HRT) and Ewalds second law. However, the remission rate for treatment of HSC- BPPV is relatively low. One of the causes for low success rate is the difficulty in determining the affected ear of HSC-BPPV. Thus, the purpose of this study was to access the efficacy of bow and lean test (BLT) for proper diagnosis of HSC-BPPV and preferable treatment outcomes. 방법:794 patients with HSC-BPPV diagnosed at the Dizziness Clinic in the Department of Otolaryngology, Ajou University Hospital between November 2004 and June 2014 were enrolled in this study. All patients underwent BLT and HRT with electronystagmography and computerized video eye movement recorder to document the nystagmus. Patients were treated using a 360 degree barbeque rotation after identification of the affected side and verification of correct diagnosis of HSC-BPPV. Patients with symmetrical intensity of nystagmus of both sides in HRT or different affected ear results in HRT and BLT were treated based on BLT results. 결과:Overall 84.1% of HSC-BPPV patients showed remission after 2 treatment sessions. The expression rate of bowing and/or leaning nystagmus was 62.1% including 200 (60.6%) for canalolithiasis and 152 (64.1%) cases for cupulolithiasis type. In comparison of remission rates between BLT-responsive and BLT-nonresponsive group, rates were higher in the BLT responsive group 91.0% versus 86.9% in canalolithiasis and 79.6% versus 71.8% in cupulolithiasis type. We also evaluated the localization of the affected ear in both HRT and BLT. 115 (41.1%) cases showed different affected ears on HRT and BLT. 결론:Bow and Lean Test may become a fundamental test for proper diagnosis of HSC-BPPV leading to successful management. Further studies will need to be focusd on causes of nonresponsive bowing and leaning nystagmus and analyze conditions for better responses.