Prescriptions of major drug classes were surveyed for one year in five teaching and five nonteaching general hospitals. Their overall rates varied over a two- to three-fold range in medicine, surgery, and pediatrics, but were uniform throughout the hospitals. Parenteral fluids and antibiotics represented over one half of the pharmacotherapy used in every specialty except medicine, where tranquilizers were the mostfrequently prescribed drugs. Prescribing patterns lacked consistency in obstetrics and newborn services, and generally with steroids, vasopressors, and anticoagulants. Significant variations also involved the use of fluids in pediatrics, diuretics in surgery, and vasodilators in medicine. These variations were too unpredictable and large to be attributed to specific differences among patient populations. Only two discrepancies were noted between teaching and nonteaching hospitals: tranquilizers were prescribed more often in the former, and vasopressors in the latter.