Diagnosis of onychomycosis requires microbiological studies, which are time-consuming. Dermoscopy is non invasive, easy and coastless method. To evaluate the diagnostic role of dermoscopy in onychomycosis and comparing its findings with microbiological results. Eighty patients with onychomycosis and 40 controls were studied for nail dermoscopic finding, and microbiological examinations in the form of microscopic examination by 20% KOH, Sabouraud dextrose agar (SDA), and HiCrome Candida Differential Agar. 72.5% of the patients were females. Most of the patient were presented with one finger (35%) and two fingers (35%). 85% of the patient were presented clinically with distal lateral subungual onychomycosis followed by total dystrophic onychomycosis (12.5%) and lastly with superficial white onychomycosis (2.5%). 52.5% and 75% of the patients were positive by direct microscopic examination with 20%KOH and SDA, respectively. Dermatophytes isolated from 7.5% of the patient, non-dermatophytes (Aspergillus) was isolated from 2.5%, and 65% had Candida by SDA. C. albicans was the commonest species (75%), followed by C. tropicalis (17.3%), and lastly C. krusei (7.7%). Dermoscopic examinations of patients showed nail spikes, longitudinal striations, and color changes in 75%, 82.5%, and 95%, respectively, with statistically significant P value (P < 0.001). There was significant difference regarding long striations and yellow colora- tion dermoscopic finding with positive KOH patients. All patients with positive culture showed nail spikes on dermoscopic examination. Dermoscopy is a rapid tool for diagnosis of onychomycosis. Longitudinal striations is the best diagnostic dermoscopic finding. Microbiological test are still needed for accurate and reliable diagnosis.