Background: The true prevalence of non-alcoholic fatty liver disease (NAFLD) is unknown in Turkey due to a lack of population-based studies. The aim of this study was (i) to determine the overall and region-specific prevalence of NAFLD in Turkey; (ii) to analyze the factors associated with the prevalence; and (iii) to determine the nationwide change in the prevalence of NAFLD in the last decade. Methods: The 10-year data (2007-2016) of 113 239 apparently healthy subjects visiting the check-up clinics of Acibadem Hospitals Group were retrospectively analyzed. A subgroup of patients (n=8120) statistically representing the bigger cohort was selected. The prevalence was analyzed according to ultrasound findings, age, sex, body mass index (BMI), geographical region, and time periods trisected as 2007-2010, 2011-2013, and 2014-2016. Results: The overall prevalence of NAFLD in Turkey was found to be 48.3%. It was highest among people >50 years of age (65.6%), male sex (64.0%), with a BMI >25 kg/m2 (63.5%), and in Central and Eastern Anatolia regions (57.1% and 55.7%, respectively). The prevalence of NAFLD was 43.5% between 2007 and 2010, 47.6% between 2011 and 2013, and 53.1% between 2014 and 2016, and the rate of increase was 22%. Multivariate analysis showed that male sex, serum alanine aminotransferase level, older age, BMI, type-II diabetes mellitus, hypertension, and dyslipidemia were independent factors associated with NAFLD. Conclusion: NAFLD is a highly prevalent disease affecting almost half of the Turkish population (48.3%). We are faced with a dramatic increase in NAFLD prevalence in the past 10 years.