To compare intravenous and orally administered corticosteroids and theophylline in treating acute episodes of airways obstruction, patients with recent worsening of obstructive symptoms were randomly divided into two groups. Group A received methylprednisolone, 80 mg/24 h, and aminophylline by continuous infusion. Group B received a comparable dose of a sustained-release theophylline and methylprednisolone, 80 mg in two equally divided doses, by mouth. Assessment of response was based on daily spirometric tests and evaluation of dyspnea and wheezing. Arterial blood gas and serum theophylline levels were also measured. The groups were comparable with respect to age, sex distribution, smoking history, and spirometric evidence of obstruction. Initial spirometric test results showed moderate obstruction, equal in the two groups. Obstruction improved markedly by both spirometric and clinical criteria in the four-day study period. The improvement in FEV1 and dyspnea index was slightly greater for group B, but the differences were not significant. We conclude that oral administration of steroids and theophylline is as effective as intravenous use in treating hospitalized patients with moderate exacerbations of airways obstruction.