OBJECTIVE To describe a patient with asymptomatic bronchial asthma and hypertension who developed an acute asthma attack after receiving sustained-release verapamil. METHODS A 66-year-old white woman with a 10-year history of hypertension and bronchial asthma was switched from immediate-release verapamil hydrocloride 40 mg tid to sustained-release verapamil 240 mg/d po for better hypertension control. After taking the first tablet, she developed dyspnea, cough, and wheezing. Antiasthmatic medications were prescribed, but the asthma symptoms did not improve. She continued taking verapamil for 6 months, then, on her own, stopped all medications including the sustained-release verapamil, and her asthma symptoms disappeared. On rechallenge she developed severe dyspnea, cough, and wheezing 20 minutes after administration. The asthma resolved within 24 hours following three albuterol inhalations. The next day similar symptoms developed with rechallenge of the same brand of sustained-release verapamil in a 120-mg formulation, and verapamil was discontinued. Six months later she was again prescribed sustained-release verapamil 240 mg in another clinic where the physician was unaware of her previous reaction. Once again, severe dyspnea, cough, and wheezing developed. CONCLUSIONS On four separate occasions the patient was challenged advertently or inadvertently, with sustained-release verapamil. Similar symptoms developed after each challenge and resolved after discontinuing this preparation. Although dyspnea associated with verapamil administration has been reported, this is the first report of an elderly asymptomatic asthmatic patient with hypertension who developed an acute asthma attack following sustained-release verapamil administration. CONCLUSIONS Sustained-release verapamil is thought to be the cause of the asthma attack in this patient because she was not taking any other preparations; the symptoms started with the administration of sustained-release verapamil and were relieved after its discontinuation.