Efinaconazole is an emerging antifungal therapy for the topical treatment of onychomycosis. Efinaconazole is an inhibitor of sterol 14α-demethylase and is more effective in vitro than terbinafine, itraconazole, ciclopirox and amorolfine against dermatophytes, yeasts and non-dermatophyte molds. Phase II studies indicate that efinaconazole 10% nail solution is more effective than either the 5% strength or 10% solution with semi-occlusion. In duplicate Phase III clinical trials, complete cure rates of 17.8% and 15.2% were demonstrated. The mean mycological cure rate for efinaconazole is similar to the oral antifungal itraconazole and exceeds the efficacy of topical ciclopirox. Efinaconazole showed minimal localized adverse events, which ceased upon stopping treatment. Overall, efinaconazole 10% nail solution is an effective topical monotherapy for distal and lateral subungual onychomycosis (<65% nail involvement, excluding the matrix) that shows further potential use as an adjunct to oral and device-based therapies.