Otomycosis usually requires long-term treatment and tends to recur. This study was performed on 87 patients with the clinical diagnosis of otomycosis and 20 controls in order to determine the pathogenic agents, predisposing factors and a cost-effective treatment. The predisposing factors included wearing head clothes (74.7 per cent), presence of dermatomycoses (34.5 per cent) and swimming (27.6 per cent). The most common pathogenic fungus was Aspergillus niger (44.8 per cent) in the otomycosis group. The only isolate was Candida albicans in the control group (2.5 per cent). We concluded that administration of four per cent boric acid solution in alcohol and frequent suction cleaning of the ear canal might be a cost-effective treatment for otomycosis since 77 per cent of the patients were treated effectively this way. Eighty per cent of the resistant cases had mixed fungal-bacterial infections, and 50 per cent of them had dermatomycoses. These resistant cases were treated by administration of tioconazole ointment.