question: IMPORTANCE: This randomized clinical trial examines the feasibility and acceptability of a decision-making tool for increasing patient interest in individualized recommendations for preventive care services. OBJECTIVE: To pilot a tool to help patients compare life expectancy gains from evidence-based preventive services. DESIGN, SETTING, AND PARTICIPANTS: This randomized clinical trial examined patient and physician responses to a pilot decision tool incorporating personalized risk factors at 3 US primary care clinics between 2017 and 2020. Eligible patients were between ages 45 to 70 years with 2 or more high-risk factors. Patients were followed-up after 1 year. INTERVENTIONS: The gain in life expectancy associated with guideline adherence to each recommended preventive service was estimated. Personalized estimates incorporating risk factors in electronic health records were displayed in a physician-distributed visual aid. During development, physicians discussed individualized results with patients using shared decision-making (SDM). During the trial, patients were randomized to receive individualized recommendations or usual care (nonmasked, parallel, 1:1 ratio). MAIN OUTCOMES AND MEASURES: Primary outcome was patient interest in individualized recommendations, assessed by survey. Secondary outcomes were use of SDM, decisional comfort, readiness to change, and preventive services received within 1 year. RESULTS: The study enrolled 104 patients (31 development, 39 intervention, 34 control), of whom 101 were included in analysis (mean [SD] age, 56.5 [5.3] years; 73 [72.3%] women; 80 [79.2%] Black patients) and 20 physicians. Intervention patients found the tool helpful and wanted to use it again, rating it a median 9 of 10 (IQR, 8-10) and 10 of 10 (8-10), respectively. Compared with the control group, intervention patients more often correctly identified the service least likely (18 [46%] vs 0; P = .03) to improve their life expectancy. A greater number of patients also identified the service most likely to improve their life expectancy (26 [69%] vs 10 [30%]; P = .07), although this result was not statistically significant. Intervention patients reported greater mean [SD] improvement in SDM (4.7 [6.9] points) and near-term readiness to change (13.8 points for top-3-ranked recommendations). Point estimates indicated that patients in the intervention group experienced greater, although non–statistically significant, reductions in percentage of body weight (−2.96%; 95% CI, −8.18% to 2.28%), systolic blood pressure (−6.42 mm Hg; 95% CI, −16.12 to 3.27 mm Hg), hemoglobin A(1c) (−0.68%; 95% CI, −1.82% to 0.45%), 10-year atherosclerotic cardiovascular disease risk score (−1.20%; 95% CI, −3.65% to 1.26%), and low-density lipoprotein cholesterol (−8.46 mg/dL; 95% CI, −26.63 to 9.70 mg/dL) than the control group. Nineteen of 20 physicians wanted to continue using the decision tool in the future. CONCLUSIONS AND RELEVANCE: In this clinical trial, an individualized preventive care decision support tool improved patient understanding of primary prevention and demonstrated promise for improved shared decision-making and preventive care utilization. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03023813