To assess the prevalence of non-communicable diseases (NCDs), and whether NCDs were treated or not, among hospitalised decontamination workers who moved to radio-contaminated areas after Japan's 2011 Fukushima Daiichi Nuclear Power Plant disaster.We retrospectively extracted records of decontamination workers admitted to Minamisoma Municipal General Hospital between 1 June 2012 and 31 August 2015, from hospital records. We investigated the incidence of underlying NCDs such as hypertension, dyslipidaemia and diabetes among the decontamination workers, and their treatment status, in addition to the reasons for their hospital admission.A total of 113 decontamination workers were admitted to the hospital (112 male patients, median age of 54 years (age range: 18-69 years)). In terms of the demographics of underlying NCDs in this population, 57 of 72 hypertensive patients (79.2%), 37 of 45 dyslipidaemic patients (82.2%) and 18 of 27 hyperglycaemic patients (66.7%) had not been treated for their NCDs before admission to the hospital.A high burden of underlying NCDs was found in hospitalised decontamination workers in Fukushima. Managing underlying diseases such as hypertension, hyperlipidaemia and diabetes mellitus is essential among this population.