The self-assessment of body weight (normal vs overweight) reported in an interview in a group of 783 men and 1085 women aged 32-83, was compared with weight and height measurements taken a few days after the interview. Among subjects with body mass indices revealing excess weight (over 27 kg/m2 in men and 45 kg/m in women), 24% of men and 15% of women reported having normal body weight. The proportion of overweight persons unaware of their condition was related to age, smoking habit, education and physical activity. In men with hypertension, the proportion of subjects unaware of being overweight was smaller by 25% compared with others. This was not the case in women. A history of cardiovascular disease, diabetes, dyspnea or poor health status had no effect on the awareness of being overweight.