This study aimed to assess body features, and alimentary and lifestyle behavior related to cancer prevention among Romanian adults having relatives with cancer. The study was performed in 2010/2011 in an oncological hospital in Cluj-Napoca, Romania. It involved 320 adults who had relatives with cancer. An anonymous questionnaire was filled in by each participants; their weights and heights were measured and body mass index (BMI) was calculated, 56.6% of the participants having a value higher than 24.9. Almost all subjects ate less than 400g of fruits and vegetables daily and 56% of the participants consumed more than 500 g of red meat weekly. One quarter of the study sample was performing less than 30 minutes of moderate physical activity daily. Some 28.1% of the subjects were smokers. These data call for comprehensive actions to help Romanian cancer patient relatives to respect the recommendations regarding healthy lifestyle promotion and cancer prevention. Health professionals should periodically assess body composition and lifestyle components of adults who have relatives with cancer in order to identify unhealthy behavior and offer them personalized education and counseling.