320 persons were tested on the nitrate content in saliva. In experiments were accounted the profession, age, sex, particularities of nourishment, drinking water, habits, diseases, taking medicines, vitamins, contact with toxic substances and so on (29 parameters). The average level of nitrates in saliva of estonians is 4.9 +/- 0.3 mg/l. The purity of teeth has the most significant influence on the nitrate content in saliva.