BACKGROUND AND OBJECTIVES: There is little research on training medical students in smoking cessation counseling (SCC). This study aimed to determine if a personal digital assistant (PDA)-based SCC tool can improve medical student SCC. METHODS: We conducted a randomized, controlled trial with third-year medical students. SCC behaviors, comfort, and knowledge were assessed using a validated survey before students attended a workshop on SCC. Student groups were then randomized to receive a paper-based reminder tool or the reminder plus a PDA-based SCC tool. The validated survey was repeated upon clerkship completion, and a videotaped standardized patient interview was assessed by trained reviewers using a 24-item SCC checklist. Focus groups assessed satisfaction with the PDA tool, usability, and barriers to use. RESULTS: SCC behaviors, knowledge, and comfort increased among all participants, with no statistical differences between groups. The PDA tool group performed 62% of key SCC activities during the videotaped interview, while the control group performed 69%. Students reported discomfort using the PDA with patients, lack of time, and lack of training as barriers to use of the tool. CONCLUSIONS: We demonstrated improvement of SCC skills by third-year medical students using a workshop combined with a supplemental reference tool. However, a PDA-based tool did not increase key SCC behaviors compared with a paper-based reminder. For a PDA intervention to be effective in this setting, the tool must be simplified and additional training provided