Abstract： Objective To investigate the risk factors of nosocomial infections in patients with head and neck cancer during radiotherapy .Methods Clinical data of 189 patients with head and neck cancer receiving radiotherapy in Huzhou Central Hospital during August 2011 and December 2014 were retrospectively studied .Chi-square test and multivariate Logistic regression analysis were performed to explore the risk factors of nosocomial infections in patients during radiotherapy .Results Among 189 patients with head and neck cancer receiving radiotherapy , nosocomial infection was observed in 64 (33.86%) patients.Univariate analysis showed that radiation-induced oral mucositis (χ2 =11.47, P<0.01), underlying disease (χ2 =6.59, P<0.05), stage of tumor Ⅲ-Ⅳ (χ2 =4.36, P<0.05), whole-neck radiation (χ2 =7.64, P <0.05), dose of radiation ≥50 Gy(χ2 =8.92, P <0.05), combined chemotherapy (χ2 =6.53, P<0.01), invasive operation (χ2 =4.21, P<0.05), PS score=1 (χ2 =3.58, P<0.05) and low body mass index (χ2 =9.56, P <0.05) were risk factors of nosocomial infections . Multivariate Logistic regression analysis indicated that radiation-induced oral mucositis ( OR=3.46, χ2 =8.72, P<0.01),underlying disease (OR=1.91, χ2 =4.66, P<0.05), stage of tumor Ⅲ-Ⅳ (OR=2.01,χ2 =5.22, P<0.05), whole-neck radiation (OR=1.78,χ2 =4.89, P<0.05), dose of radiation ≥50 Gy (OR=1.69,χ2 =3.25, P<0.05), combined chemotherapy (OR=1.84, χ2 =6.91, P<0.05) and low body mass index (OR=1.53, χ2 =2.59, P<0.05) were independent risk factors of nosocomial&nbsp;infection.Conclusions Nosocomial infections are popular in patients with head and neck cancer during radiotherapy.Radiation-induced oral mucositis, underlying disease, stage of tumor, radiation field, dose of radiation, combined chemotherapy and body mass index are associated with the occurrence of nosocomial infections in these patients .