The purpose of the present investigation is to reveal the specifics of the nutrition, nutritional behavior (habits), the prevalence of obesity and of certain chronic diseases among workers. The subjects were 264 workers (203 males and 61 females) from the ammonium production department of a fertilizer plant, divided into two age groups: under and over 30 years of age. The data were collected by means of a food-frequency questionnaire about daily nutrition and the average quantity of food. The nutritional status was assessed on the basis of BMI. All workers underwent clinical examinations conducted by a range of different experts, including an internal diseases specialist, a neurologist, a cardiologist, an opthalmologist, an otorhino-laryngologist, and a dermatologist. Twenty hematological and biochemical indicators in blood and serum were measured. Assessment of the individual energy intake showed that hyperenergetic nutrition was typical of 67% of workers because of extra intake of fat, which was seen in 87.9% of all individuals examined. The daily fat intake of over 40E% was typical for almost half the females (45.9%). All age and gender groups displayed hyperprotein nutrition with pronounced cellulose (fiber) deficit and a high daily sodium intake. The frequency of overweight individuals (BMI = 25, 1-30 kg/m2) was 43.9%, whereas that of obese individuals (BMI = > 30 kg/m2) was 23.1%. A total of 67% of workers had excessive body mass. The hypertension prevalence rose significantly from 6.9% in Group I to 34.5% in Group II, and to 57.4% in Group III. Coronary heart disease was rare, but the seven cases registered were among the overweight workers. The radiculitis prevalence among workers with normal body mass was two-fold lower in comparison with both groups (overweight and obesity). We conclude that hyperenergetic and unbalanced nutrition is a factor that determines the prevalence of overweight and obesity. A significantly higher percent of overweight and obese workers suffered from hypertension, liver disease, diabetes, coronary heart disease, and eye-vessel diseases. A tendency toward rising radiculitis and musculoskeleton system disease prevalence was seen that parallels the increase in BMI.