Passive surveillance (PS) is a traditional approach to communicable disease surveillance. To complement the approach, several countries have adopted active surveillance (AS) systems that involve the voluntary participation of physicians. This study compares AS versus PS systems in Korea based on the systems' reporting propensity of chickenpox. A mail questionnaire survey was conducted with a random sample of physicians involved in the PS system (N=1,955) and all sentinel physicians of the AS system (N=193). Multiple regression analysis was conducted to identify factors associated with reporting propensity. The reporting propensity of physicians in the AS system was significantly higher than that in the PS surveillance system, 2.7 versus 1.9 on a 5-point Likert scale (p<0.05). Multiple regression analysis showed that, in addition to the type of the surveillance system, physician knowledge of chickenpox as a notifiable disease and the type of institution with which a physician was affiliated were significant factors for a physician's reporting propensity. For both systems, the common barriers for reporting were 'lack of confidence in diagnosis,' 'burden from interference by the public health department following reporting,' and 'complexity of the reporting system.' In conclusion, AS of communicable diseases appeared to have a significantly better performance compared to PS in Korea in the case of chickenpox reporting. These findings would be useful for countries concerned with developing more effective strategies for improving the reporting rate of notifiable diseases.