In terms of both diagnosis and treatment, onychomycosis remains a problem in Indonesia. To examine this situation, we performed a retrospective study of the incidence of onychomycosis involving 10 state university hospitals across the country. We collected data from medical records of patients treated at these hospitals in 1997-1998 (study 1) and from a 1998-1999 multi-center Indonesian study on pulse-dose itraconazole therapy (study 2), both of which were part of onychomycosis campaigns with the objective of increasing the awareness of physicians of onychomycotic problems. Further, we analyzed data from year 2003 medical records of patients from 4 hospitals in Java (study 3). The average incidence of onychomycosis among fungal diseases increased to 4.7% in large cities that, from an average incidence within Indonesia of 3.5% in 1997-1998. At only 0.5%, the incidence of onychomycosis among all skin diseases was low in both study 1 and 3. Female patients outnumbered male patients with a ratio of 1.5:1 to 2:1. In study 2, the fingernail was the site most frequently affected. KOH examinations and fungal culture in study 1 (n=557) showed causative organisms to be Candida (50.1%), dermatophytes (26.2%), moulds (3.1%) and mixed infections (1.8%), with the remainder (18.7%) unidentified. Similar frequency of causative organisms was reported in study 2 (n=113) and in study 3 (n=183). People's low awareness of nail disease and consequent lack of concern as well as the limited diagnostic ability of KOH examination and fungal culture might influence the low incidence of the disease and the frequency of detection of the causative organisms.