Onychomycosis is a fungal infection of nails caused by dermatophytes, yeasts or nondermatophyte molds and represents about 30% of mycotic cutaneous infections. Increasingly onychomycosis is being viewed as more than a mere cosmetic problem. In spite of improved personal hygiene and living environment, onychomycosis continues to spread and persist. The prevalence rate of onychomycosis is determined by age, predisposing factor, social class, occupation, climate, living environment and frequency of travel. Onychomycosis in immunocompromised patients can pose a more serious health problem. Dermatophytes are the most frequently implicated causative agents in onychomycosis. Previously regarded as contaminants, yeasts are now increasingly recognised as pathogens in fingernail infections, as are some moulds. Clinical diagnosis of onychomycosis is based on the patients' history; a physical examination, microscopy and culture of nail specimens. The treatment of onychomycosis has been attempted throughout the ages, but only in the last two decades have safe, effective systemic treatments been available for this chronic superficial fungal disease. Oral Griseofulvin and Ketoconazole; once the agents of choice for the treatment of onychomycosis, have been superseded by newer systemic compounds that have a higher cure and lower relapse rates, cause fewer side effects and are suitable for short-term dosing.