Gingival hyperplasia (GH) occurs in 20 % to 40 So of all patients receiving long-term oral phenytoin therapy and phenytoin is probably the most common cause of GH in children and young ado1escents.l Several other drugs including nifedipine, a calcium channel blocker, have been reported infrequently to cause GH.2-4 We report here a similar GH in two children following the long-term administration of a large dose of verapamil for the management of supraventricular tachycardia (SVT). Verapamil-associated GH has not been reported previously in the English literature. Case Ntj. 1. SL is a 12-year-old girl who was first noted to have tachycardia during the prenatal period. She had a trial of digoxin, quinidine, and propranolol in high doses in various combinations, with partial control of her SVT. At 3 years of age, a diagnosis of a permanent form of junctional reciprocating tachycardia (long R-P’ tachycardia) was made by electrophysiologic study, and an intravenous verapamil trial (0.2 mg/kg) was successful. She had no ventricular dysfunction by echocardiography. She was started on oral verapamil, 80 mg twice a day (9 mg/kg/day), with partial control, and was maintained on a similar dose with respect to body weight for the next 4 years. At 7 years of age, she was changed to sustained-release verapamil, 240 mg twice a day (15 mg/kg/day). Following 2 weeks of therapy on this dose, her verapamil level was 1030 Fg/L and 590 PglL at 6 hours and 12 hours, respectively, after the oral dose of verapamil (therapeutic trough level 100 to 600 pg/ L). Following 6 weeks of verapamil therapy, she developed marked GH. The labial gingivae of the anterior maxillary and mandibular teeth were firm, red, and nodular, with minimal bleeding. Despite good dental hygiene and frequent dental visits, she had persistent GH. There were no other adverse effects of verapamil. At 11 years of age verapamil was discontinued because of partial control of the tachycardia. Six weeks later her GH significantly improved. Subsequently she was started on a regimen of oral propafenone without success. At present she is maintained on a regimen of oral Aecainide with fairly good control of the tachycardia. Case No. 2. DM is a 16-year-old young woman patient who was noted to have a tachycardia during the prenatal