Objective To understand the underreporting of reportable infectious diseases in medical institutions in Nanyang. Methods According to stratified random sampling requirements, 13 counties were selected, over and above the county level 1 general hospitals, specialist 1 hospitals, 1 township hospitals and 2 village clinics. Refer to 2013 annual outpatient log, out of hospital registration, laboratory and department of radiology registration, and spot checks of reportable diseases. Results In the survey of medical institutions at all levels of 66, the county level and above, 13 general hospitals, 13 township hospitals, 26 village clinics, special hospital 14. It was found that among 755 cases of legal infectious diseases, 16 were not reported, the underreporting rate was 2.12%; the B, C Class infectious diseases and the rates were 1.51%, 3.57%, no significant difference (χ²=2.319, P=0.128); the county, township, village and specialist the medical institution of infectious diseases and the rates were 1.76%, 1.92%, 5.56%, 2.72%, no significant difference (χ²=1.614, P=0.656). Conclusion There are underreporting of reportable infectious diseases in medical institutions in Nanyang.