Background: Onychomycosis can be confused with other onychopathies clinically. Nail dermoscopy (onychoscopy) could be helpful in the differential diagnosis between onychomycosis and other onychopathies, but well-designed comparative case-control study has not been reported yet. Objectives: The aim of this study is to evaluate the usefulness of the nail dermoscopy for the diagnosis of onychomycosis in comparison with other onychopathies. Methods: Two hundreds seventy patients with mycologically-proven onychomycosis and 100 patients with other onychopathies as the control group were enrolled in the study. Dermoscopic examination was performed with handheld dermoscope with liquid medium and retrospective image analysis was done. Results: Chromonychia of nail plate (78.5%), longitudinal striae (55.9%), thickening of nail plate (43.3%), jagged edge with spike (38.9%), subungual keratosis (38.9%), ruin aspect (31.1%) and mushroom cloud (18.1%) was more common in onychomycosis compared as other onychopathies, with statistically significant difference (p<0.001). Among those features, jagged edge with spike and mushroom cloud sign were observed in solely onychomycosis, which were regarded as the most specific features of the onychomycosis. Conclusion: The distinct dermscopic features described herein can help clinicians to facilitate diagnosis of onychomycosis distinguishing from other onychopathies.