To examine whether Palm Prevention, a free software tool for Palm OS personal digital assistants (PDAs) that provides quick access to preventive guidelines in a patient-specific manner at the point of care, improved adherence to five preventive measures in primary care. Prospective intervention pilot study. Vancouver, BC, and surrounding area. Eight general practitioners. Each physician used Palm Prevention for five preventive measures during routine preventive health visits with 10 patients (n = 80). Charts of consenting patients were reviewed for documentation of recommended maneuvers. Rates of adherence to five evidence-based guidelines selected from the Canadian and American task forces on preventive care and incorporated into Palm Prevention. Intervention and control physicians were similar in their familiarity with and use of PDAs, and they recruited similar patients for the study. Intervention and control groups had similar rates of screening for hypertension. Intervention improved adherence to the remaining four guidelines: cervical cancer screening increased 22% (only absolute increases are reported); hyperlipidemia screening increased 30%; colorectal cancer screening increased 27%; and prophylaxis with acetylsalicylic acid in high-risk patients increased 38%. Participants were surveyed after the study; all reported that they found the software helpful and would continue using Palm Prevention. Usage statistics showed that study participants used the tool outside the trial: users entered between 28 and 68 unique patients into the program during the 2-month intervention. This pilot study suggests PDAs are useful in improving preventive care and facilitating translation of knowledge into practice. This was particularly apparent with newer guidelines.