The study compared nail sampling for fungal culture in suspected onychomycosis in 1843 nail units: 791 conventionally and 1052 guided by dermoscopy. Dermoscopy made it possible to target areas with specific features, such as spikes, a ruin-like pattern, and longitudinal stripes. The rate of positive cultures was significantly higher in the dermoscopic group (72.5% vs. 66.0%, P < 0.0001). Dermoscopic features strongly predicted a positive outcome: spikes (OR 5.31), ruin-like pattern (OR 4.31), and longitudinal furrows (OR 2.21, all P < 0.001). Multivariate analysis confirmed that dermoscopically guided collection is an independent predictor (adjusted OR 1.63). The contamination rate was low (1.4%) and the most frequent pathogen was Trichophyton rubrum (75.2% of positive cultures). The authors concluded that dermoscopy improves diagnostic yield by targeting viable fungal reserves. Integration into the routine is simple and non-invasive.