Objective: (1) To investigate an association between conscientiousness of personal traits (prepared, followed a schedule, ordered, paid attention to details, self-disciplined) and user-based practices of medication safety (UPMS). (2) To assess the short-term (4-month) learning effect of the educational medication safety lecture.Material & method: (1) A cross-sectional study was used. Questionnaires (adding items about conscientiousness of personal traits) were given to those who participated in the Vital Health Stations activities in Taoyuan in April or August 2009. (2) A singlegroup pretest and posttest trial was conducted. Those who attended the two Vital Health Stations activities repeatedly were eligible.Results: (1) In total, 1860 valid questionnaires were used. The mean score of UPMS was 31.4, out of 40. Multiple linear regression on UPMS revealed that conscientiousness of personal traits was the first factor included. (2) 175 questionnaires were used. Except for one item, all single items and the total score of UPMS significantly improved four months after the educational medication safety lecture.Conclusion: We concluded that conscientiousness of personal traits is associated with practicing medication safety. There was also a short-term learning effect from the medication safety lecture.