Recent advances in our understanding of the neurophysiology and neuropharmacology of the lower urinary tract have improved our ability to treat disorders of bladder and urethral function. Similarly, many classes of drugs used in treating various medical conditions can cause lower urinary-tract symptoms and dysfunction. Based on objective urodynamic evaluation, the clinician is able to sort out bladder and urethral abnormalities and scientifically choose appropriate pharmacologic regimes to treat these conditions. This article reviews lower urinary-tract physiology and provides the clinician with a rational, objective, neuro-pharmacologic approach to lower urinary-tract disorders.