Guided dosing within a computerized provider order entry (CPOE) system is an effective method of individualizing therapy for patients. Physicians' responses to guided dosing decision support have not been extensively studied. As part of a randomized trial evaluating efficacy of dosing advice on reducing falls in the elderly, CPOE prompts to physicians for 88 drugs included tailored messages and guided dose lists with recommended initial doses and frequencies. The study captured all prescribing activity electronically. The primary outcome was the ratio between prescribed dose and recommended dose. Over 9 months, 778 providers entered 9111 study-related medication orders on 2981 patients. Physicians using guided orders chose recommended doses more often than controls(28.6% vs. 24.1%, p<0.001). Selected doses were significantly lower in the intervention group (median ratio of actual to recommended 2.5, interquartile range [1.0,4.0]) than the control group (median 3.0 interquartile range [1.5,5.0], p<0.001). While physicians selected the recommended dose less than a third of the time, guided geriatric dosing modestly improved compliance with guidelines.