Solanum xanthocarpum and Solanum trilobatum are widely used to treat respiratory diseases in southern Indian traditional medicine (Siddha). A pilot study was undertaken to investigate the clinical efficacy and safety of a single dose of the above herbs in mild to moderate bronchial asthma. The respiratory functions (FVC, FEV1, PEFR and FEF25-75%) were assessed by using a spirometer prior to and 2 h after oral administration of 300 mg powder of whole plant of either S. xanthocarpum or S. trilobatum. Standard bronchodilator drugs, salbutamol (4 mg) and deriphylline (200 mg) were used for comparison. Treatment with either S. xanthocarpum or S. trilobatum significantly improved the various parameters of pulmonary function in asthmatic subjects. However, the effect was less when compared to that of deriphylline or salbutamol. No untoward effects were reported during the study. The results of the present study confirm the traditional claim for the usefulness of these herbs in bronchial asthma. More detailed studies are required to investigate the mechanism of action and therapeutic utility of S. xanthocarpum and S. trilobatum.