Three out of nine unstable asthmatics whose asthma is subjectively and objectively better controlled on continuous subcutaneous terbutaline infusions (6-12 mg/24 hours) developed tender indurated subcutaneous swellings at the infusion site. In the two cases reported here in detail, histologically the lesions were areas of panniculitis and deep dermal collagen necrosis. Further investigation of the possible causative mechanism for these lesions--drug solution pH, osmolality, or impurities--suggests that impurities in the solution are the most likely cause.