Therapeutically administered antidiabetic drugs, notably insulin and the sulfonylureas, are undoubtedly the most common cause of hypoglycemia encountered in clinical practice. Nevertheless, an impressive list of other drugs can produce hypoglycemia unpredictably in seemingly healthy individuals in whom it may masquerade as spontaneous hypoglycemia. Unless the true cause is identified when the patient is first seen, fruitless and expensive overinvestigation may ensue. The most important drugs are discussed herein and brief mention made of those for which coincidence has not been eliminated.