Abstract: Objective To understand the underreporting of notifiable communicable diseases in Tianjin from 2004 to 2012 and provide evidence for developing measures to standardize communicable disease reporting. Methods The data about communicable disease reporting during this period in Tianjin, which were collected through the surveys conducted according the national communicable disease underreporting survey protocol, were used to evaluate the performance of communicable reporting with software SPSS 11.5. Results According to the survey during this period, a total of 18 153 communicable disease cases occurred, but 1214 were not reported, the underreporting rate was 6.69%. The underreporting rate decreased with year, the differences in annual underreporting rate were statistically significant (2=914.73, P=0.000). The underreporting rate of communicable diseases in Class C was significantly higher than that in Class B, the difference was statistically significant (2=52.54, P=0.000). The management of communicable disease reporting during 2004-2008 and during 2009-2012 were different, but the underreporting rates in medical institutions at grade Ⅰ, Ⅱ and Ⅲ were all in decline during these two periods, the difference had statistical significance. The higher the grade was, the more the underreporting rate declined (Mantel-Haenszel: 2=562.13, P=0.000); Conclusion Strengthening the implementation of the Communicable Disease Prevention and Treatment Law and other relevant regulations, improving the supervision for communicable disease reporting can greatly reduce the underreporting of communicable diseases. The quality of communicable disease reporting varied with the medical institutions at different levels due to the different management practice and informatization level.