Objectives: Previous studies have indicated that cardiopulmonary resuscitation by some healthcare professionals does not measure up to current standards. We evaluated the attitude, knowledge, and behavior of healthcare professionals towards basic life support courses at the Postgraduate Training Center in Riyadh, Saudi Arabia. Methods: Crosssectional and longitudinal analyses were performed. Data were initially collected after each basic life support course over 11-months. A follow-up questionnaire was sent 6-months after each course. The Kirkpatrick model was used to assess the effectiveness of the course for improving attitudes, knowledge, and behavior. Results: Total 455 trainees (87.5%) and 53 instructors (88.3%) responded at baseline. The mean attitude and knowledge scores were 55.6 ± 6.09 and 92.1 ± 7.06, respectively. After 6-months, 193 individuals responded. The mean knowledge score difference was -9.27 ± 12.9. The mean behavior score was 43.2 ± 4.29 at baseline; after 6-months, 26.4% of participants showed a decline in confidence in their cardiopulmonary resuscitation skills. Attitude and behavior scores were correlated (p<0.001). Conclusion: Healthcare professionals had generally positive attitudes and behavior concerning basic life support. There was a clear deterioration in basic life support knowledge 6-months after the course. To ensure the delivery of high-quality cardiopulmonary resuscitation, frequent training and knowledge assessment are imperative.