Background: environmental influences on alcohol use in patients with mental disorders have received little research, although they may be another determinant of alcohol use beyond illness. The aim was to study the influence of family traditions and social environment on alcohol consumption by patients with mental disorders. Patients: 106 patients with various mental disorders who received treatment in inpatient and outpatient settings. Methods: patient information was received from the medical record and interviews using questionnaire “Alcohol use: experience, pattern, treatment” and scales: Alcohol Use Disorders Identification Test (AUDIT), Udvalg for Kliniske Undersogelser Scale (UKU), Drug Attitude Inventory-10 (DAI-10). Results: the proportion of patients with high risk for alcohol use problems was 21% of all patients. Patients with a high level of risk differed in the style of drinking alcohol in the parental family: their parents drank alcohol more often. These patients also had their first experience of drinking alcohol in their parental family. There were more people who drank alcohol in large quantities in the past environment of such patients. Although high-risk patients had changed their current environment, they were still more likely to make situational alcohol choices, use it more often to cope with difficulties, and appeared to use previously established drinking styles. All high-risk patients began drinking alcohol before the onset of the disease. Conclusions: patients with a high risk of problems with alcohol use are more likely to have learned their drinking style from their parents, and they are more likely to drink alcohol under the influence of the situation. However, one third of patients were able to reduce their alcohol consumption during illness.