OBJECTIVE: There is increasing focus on non-alcoholic fatty liver disease (NAFLD). The aim of the present study was to conduct a long-term clinical follow-up of patients with biopsy-confirmed fatty liver without inflammation or significant fibrosis (pure fatty liver), to analyse for potential risk factors at the time of index liver biopsy important for survival and the development of cirrhosis and to describe the causes of death. MATERIAL AND METHODS: Patients were linked through their personal identification number to the Danish National Registry of Patients and the Register of Causes of Death. All admissions, discharge diagnoses and causes of death during follow-up were collected. All surviving patients were invited to a clinical follow-up. RESULTS: The follow-up period was 20.4 and 21.0 years, respectively, for the NAFLD and alcoholic fatty liver disease (AFLD) groups. Two NAFLD patients (1.2%) developed cirrhosis during the follow-up period versus 54 (22%) AFLD patients. Sixty-four percent of 178 surviving patients out of an original cohort of 417 patients attended the clinical follow-up. In NAFLD patients, none of the risk factors studied was significant in relation to the risk of death. Patients with AFLD died primarily from cirrhosis and other alcohol-related disorders, whereas in patients with NAFLD the main causes of death were cardiovascular disease and cancer. CONCLUSIONS: For patients with pure non-alcoholic fatty liver, survival was good and independent of the histological, clinical and biochemical characteristics at the time of biopsy; the main causes of death were cardiovascular disease and cancer.