Abstract: Objective To analyze the causes of underreporting of notifiable communicable diseases in Maoming, and provide evidence for improvement of communicable disease reporting and better control of epidemic. Methods The statistical analysis was conducted on registering and reporting data of communicable disease cases from 2007 to 2009, which were collected from the all medical institutions in Maoming by checking their outpatient departments, admission and discharge, laboratory, radiology department and communicable diseases records. Results The underreporting rate of notifiable communicable diseases was 12.67% in Maoming during this period. The underreporting rate in township health centers was highest, and the main diseases which were highly underreported were gonorrhea, dysentery and viral hepatitis. Conclusion It is necessary for health authority to strengthen the supervision of communicable disease reporting and necessary for health institutions to practice rewards and penalties, set up feedback system of diagnosis Results in order to reduce underreporting of communicable diseases.