Allergic fungal sinusitis is a non-invasive disease, first described in the early 1980s. We review our experience with 25 patients treated at the University of Texas Medical Branch, Galveston. All patients were treated surgically, using endoscopic techniques in 17, and combined endoscopic and external procedures in eight. Histological evidence of tissue invasion was absent in all 25 patients, in spite of extensive destruction of the skull base in four. Dematiaceous fungi were the most common cultural isolate. Fifteen patients were available for more than 6 months post-operative follow-up. None of the eight patients who developed recurrent disease had been treated with post-operative systemic steroids. Four of the seven patients who remained disease-free had received steroids. Clinical trials to test the efficacy of systemic steroids in the prevention of disease recurrence are clearly warranted.