The purpose of this study was to investigate the prevalence of metabolic syndrome (MetS) and its components in relation to different Body Mass Index (BMI) categories in young Finnish males. Different components of MetS were assessed in 1099 healthy Finnish male military conscripts of about 19 years of age. Prevalence of MetS and its components, according to criteria given by the International Diabetes Federation (IDF) and the National Cholesterol Education Program Adult Treatment Panel III (ATPIII), were calculated for different BMI categories. Based on the complete sample, prevalence of MetS, according to IDF and ATPIII criteria, was 6.8 and 3.5%, respectively. MetS prevalence increased in parallel with an increase in BMI. In obese persons it occurred in 55.4 and 27.2% according to IDF and ATPIII criteria, respectively. Our observations on MetS prevalences (which were especially high in obese service men) were in line with those few studies carried out earlier in the USA. We recommend that health education focus on those individuals that show an elevated risk of developing, already in young adulthood, cardiovascular disease and type 2 diabetes.