Nasal polyps are commonly treated surgically. Intranasal administration of topical corticosteroids has gained increased acceptance as a treatment alternative. The aim of our study was to compare the efficacy of treatment of two formulations of budesonide with placebo on nasal polyps. At four Danish clinics 138 patients suffering from moderate or severe nasal polyps were randomized to a twice daily treatment with Rhinocort Aqua 128 micrograms, Rhinocort Turbuhaler 140 micrograms or placebo (Astra Draco, Sweden) for 6 weeks. Polyp size (primary efficacy variable), nasal symptoms, sense of smell, and patients' overall evaluation of treatment of efficacy were assessed by scores. Polyp size was reduced significantly in both budesonide treated groups compared with placebo, but there was no statistical difference between the two actively treated groups. Patients' nasal symptom scores was significantly more reduced in the Aqua compared to the Turbuhaler treated group, and both reduced symptom scores were significantly better compared to placebo. Sense of smell was significantly improved in the actively treated groups compared to placebo. The proportion of patients rating substantial or total control over symptoms after 6 weeks treatment was 60.9% and 48.2% in the Aqua and Turbuhaler-treated groups, respectively, which was significantly better compared with 29.8% in the placebo-treated group. Rhinocort Aqua and Rhinocort Turbuhaler were equally well tolerated.