The prevention of chronic diseases, especially metabolic disorders, is based on modification of behavioural risk factors, in particular eating habits and physical activity. Numerous population studies have demonstrated a relationship between regular physical activity and decreased levels of risk factors for CVD (cardiovascular disease), type 2 diabetes and some cancers. Increasing the level of physical activity as part of the programs implemented for disease prevention or health promotion for selected populations requires a behavioural diagnosis, whereby an essential element is the preferred leisure-time activity in terms of the structure of negative health indicators. Evaluation of physical activity under population studies requires a simple, validated and inexpensive tool to be used in medical practice or health promotion. The Minnesota Leisure Time Physical Activity Questionnaire (MLTPAQ) is a tool currently often used and validated with laboratory methods. Standard MLTPAQ allows for assessment of the level of physical activity undertaken in leisure time. The authors present an algorithm for assessing leisure-time physical activity level based on MLTPAQ. The paper also reviews the practical application of the MLTPAQ questionnaire on healthy and patient populations in Poland and other countries by specialists in public health, health promotion and in medical practice.