The data of postal questionnaire were compared to those obtained as a result of examination (anthropometry) of a random sample (n-806) of persons working at one of the Moscow industrial enterprises. It has been shown that the postal questionnaire makes it possible to assess the body weight with an accuracy of up to +/- 3 kg in 67 percent of men and in 69 percent of women. Meanwhile the height could be assessed with an accuracy of up to +/- 3 cm in 93 percent of men and in 80 percent of women. The relationship was established between the error made in the subjective assessment of the body weight and the genuine magnitude of the body weight. The possibilities of correcting the data obtained have been also demonstrated. The postal questionnaire permits the identification of excess body weight (Quetelet's index over 28) in 68 percent of men and in 78 percent of women and can be used for studying the prevalence of excess body weight among the population without employment of additional manpower for examinations.