With the current rapid introduction of new drugs on the market, drug toxicity and side effects have received increasing publicity in the literature. Bladder dysfunction, however, rarely has been reported as an adverse effect. The possible mechanisms in the induction of urinary incontinence by three main groups of drugs, the neuroleptics, the antihypertensive agents, and the drugs used in the treatment of neurogenic bladder obstruction, are reviewed. These drugs are thought to act peripherally at sympathetic neurons or through a centrally-mediated effect.