Background: This study aimed to investigate the incidence of and potential risk factors for acute radiationinduced dermatitis (RID) in patients with gynaecological malignancies who underwent intensity-modulated radiation therapy (IMRT).Methods: Ninety-six patients, who were diagnosed with gynaecological malignancies and underwent IMRT in the lower vagina and/or groin at Zhejiang Cancer Hospital (Hangzhou, Zhejiang, China) between January 2012 and June 2014, were enrolled. Clinical data were retrospectively collected. Acute RID grade ≥2 severity was defined as clinically relevant acute RID and sub-grouped accordingly. Univariate and multivariate analyses were performed.Results: The incidence of grades 0, 1, 2, 3, and 4 acute RID was 2.1%, 43.8%, 35.4%, 18.8%, and 0%, respectively. Univariate analysis revealed that clinically relevant acute RID was independently correlated with hyperglycaemia (defined as venous fasting blood glucose level ≥7.1 mmol/L for 2 consecutive measurements), concurrent chemotherapy, and prophylactic use of triethanolamine emulsion (P<0.05). Patient age (P=0.521), body mass index (BMI) (P=0.893), and radiation boost (P=0.870) were not statistically significant factors.All variables with P<0.1 were included in the multivariate analysis together with radiation boost. Similarly, clinically relevant acute RID was independently correlated with hyperglycaemia [odds ratio (OR) 3.150; 95% confidence interval (CI), 1.019-9.736; P=0.046], synchronous chemotherapy (OR 3.515; 95% CI, 1.362-9.072; P=0.009), and prophylactic use of triethanolamine emulsion (OR 0.412; 95% CI, 0.170-0.998; P=0.049).Conclusions: Hyperglycaemia and synchronous chemotherapy were independent predictive factors for clinically relevant acute RID. Prophylactic use of triethanolamine emulsion may help to reduce the incidence of clinically relevant acute RID.