Background. During pregnancy the changes of biochemical parameters in the saliva i.a. the increase of α-amylase activity were observed. The increased α-amylase activity level may be hypotheticaly associated with the increased predisposition of caries progress. This enzyme takes part in the process of decomposition of complex sugars to simple sugars, which make basic substrate for caries-causing bacteria. Objectives. Assessment of α-amylase activity in the saliva of pregnant woman in reference to non-pregnant females and monitoring of α-amylase level, as pregnancy advances. In additon, attempt of assesement of influence to changes of hormons activities in saliva observed during pregnancy as a risk factor of caries was performed. Material and Methods. The study involved 30 pregnant and 30 non-pregnant females (control group). The studied group was undergone an examination in the first (G1), in the second (G2) and in the third trimester of the pregnancy (G3). The control group - a one-time examination, on the 7th day following the first day of the last menstruation (G0). In non-stimulated mixed saliva α-amylase activity level by Caraway colorometric method, total zwia{ogonek}protein (B) by Lowry method as well as salivary flow rate (V) were assessed. Dental condition was evaluated using DMF/T index and the advancement of carious lesions by WHO criteria D1-D4. Results. The α-amylase activity level was higher in the pregnant group than in the control group and significant higher level of α-amylase activity in the third examination was observed (63.02 ± 44.48 J/ml vs. 117.66 ± 91.57 J/ml, p < 0.01). Along with the advancement of pregnancy a significant increase of α-amylase activity was observed, the level of α-amylase activity in the third examination was higher than in the first and second examination. The significantly lower value of DMF/T index among control group in comparison with pregnant females was observed (DMF/T 8.80 ± 5.78 vs. 11.86 ± 4.47 vs. 11.86 ± 4.48 vs. 12.09 ± 4.41, p < 0.01). Higher number of existing carious lesions (D/T) and significant higher number of decays involved dentine among the studied group in comparison with non-pregnant group were observed. Conclusions. As pregnancy advances significant increase in α-amylase activity was observed. Direct correlation between level of activity of salivary α-amylase and development of pregnant women's hard tissue caries was not observed.