Assessment of schoolchildren's knowledge, attitudes, and practices towards influenza A (H1N1) is crucial as schools play a major role in spreading the infection. The aims of this study were to determine the level of knowledge, attitudes, and practices on influenza A (H1N1) and the factors associated with practices of preventive behavior.A cross sectional study was conducted from July until December 2010. Two public secondary schools for two districts in Kelantan, Malaysia were randomly selected. Data were collected using a self-administered questionnaire. The questionnaire consisted of five constructs: sociodemographic, risk factors of containing influenza A (H1N1) infection, knowledge, attitudes, and practices. The questionnaire had been te,sted for its construct validity and reliability. General linear regression was applied in the data analysis. A sample of 436 secondary school students were recruited in this study involved Malay students aged 16 years old. The total knowledge, attitudes and practices scores for the overall respondents were 69.4, 82.2, and 73.8%, respectively. The significant influencing factors for the practices of preventive behavior were attended talk on H1N1 and attitudes score.This study suggested that health education is important for promoting the health of adolescents and contributing to the overall health of the public so that they will take precautions against the H1N1 infection.