Onychomycosis shows a poor response to current topical, oral, or device-related antifungal therapies. The aim of this study was to identify factors influencing the cure rates of non-dermatophyte mold and Candida onychomycosis. Eighty-one patients who completed treatments were divided into "cured" and "non-cured" groups. The statistical significance of differences between the two groups was studied. Male gender (P < 0.01), long duration of disease before the initiation of treatment (P < 0.02), three or more infected nails (P < 0.0002), continuous exposure to water and detergents (P < 0.05), frequent exposure to mud and soil (P < 0.01), barefoot walking (P < 0.025), concomitant diabetes and hypertension (P < 0.04), eczema (P < 0.03), and associated paronychia (P < 0.01) had negative effects on cure rates of onychomycosis. Patient age, occupation, site of illness (hand, foot or big toe), type of disease (distal and lateral subungual onychomycosis, proximal subungual onychomycosis or total dystrophic onychomycosis), pathogenic fungi, and treatment modality had no statistically significant impact on cure rate. To minimize the failure rate of antifungal therapies in the treatment of onychomycosis, patients are advised to start treatment as soon as possible, and to avoid predisposing factors such as exposure to water, detergents, mud and soil, and barefoot walking.