Assessing and improving informed consent understanding is equally important as obtaining consent from participants in clinical trial research, but developing interventions to target gaps in participants' informed consent understanding remains a challenge. We used a randomized controlled study design to pilot test an educational intervention to improve actual informed consent understanding of new enrollees in the Adult AIDS Clinical Trial Group (AACTG). Questionnaires were administered to 24 enrollees to assess their baseline understanding on eight elements of informed consent associated with AIDS clinical trials. Enrollees who scored 18/21(85%) or less were randomly assigned to in-person, targeted education (intervention), or delayed education (control). Two follow-up assessments were administered. Repeated measures ANOVA was performed to determine intervention effectiveness in improving actual informed consent understanding over time. Actual understanding improved at the immediate post-intervention time point with a significant score difference of 2.5 when comparing the intervention and delayed groups. In addition, there was a significant score difference of 3.2 when comparing baseline to three-month follow-up for the two groups, suggesting a statistically significant intervention effect to improve actual understanding of the basic elements of informed consent. The findings demonstrated that one-time targeted education can improve actual informed consent understanding one week after the intervention, but retention of these concepts may require periodic monitoring to ensure comprehension throughout the course of a clinical trial.