The treatment of chronic hypertension in patients unable to take oral medications is challenging. Little information on the comparative safety and efficacy of i.v. alternatives is available. Hydralazine, methyldopate, enalaprilat, and nicardipine appear to be the best options for patients temporarily requiring i.v. medications for controlling chronic hypertension. Therapy should be selected on the basis of the individual patient's needs and diseases, the potential for adverse events, the monitoring required, drug costs, and the expected duration of therapy. The choices may be limited, but understanding the proper use of i.v. antihypertensives should enhance blood pressure control and patient care.