We examined the efficacy of nedocromil sodium as an oral steroid sparing agent in a group of 37 severe, oral steroid-dependent asthmatics. All were receiving daily or alternate-day prednisone. These patients had taken part in an earlier, 12-week double-blind trial of nedocromil sodium 16 mg daily by inhalation or matching placebo. They continued with test treatment (26 patients on nedocromil sodium and 11 on placebo) on a double-blind basis for a further 12 weeks. During this time, patients visited the clinic every 2 weeks, when asthma severity and symptoms were assessed. On the basis of these assessments, the dose of oral steroid was either decreased, or maintained at the same level, or the patient was withdrawn if the asthma had deteriorated to a clinically unacceptable level. The nedocromil sodium group was able to achieve a greater percentage reduction in oral steroid dose (P less than 0.05). The rate of withdrawal due to worsening asthma was 31% from active and 55% from placebo treatment. Trends in other variables (time before withdrawal and numbers of patients able to withstand complete removal of oral steroids) favoured nedocromil sodium but the differences between the groups were not statistically significant.