Gestation and lactation are times when females mammals have high energy expenditures. There is a strong relationship between a female's physiological state and her food requirements and absorption of nutrients and energy needs. The aim of these morphometric studies on the alimentary canal in control (nonpregnant and nonlactating) and pregnant and lactating females of the common shrew (Sorex araneus) was a comparative analysis of changes in the mucosa of subsequent regions of the digestive tract. The physiological state of the female (during gestation and lactation) was reflected by the anatomic structure of some sections of the alimentary canal. The length of the esophagus increased by 24.3% in females in late gestation relative to the control group, but its length in lactating females was close to that of females in the early stage of gestation. The duodenum of females in late gestation or during lactation was 39.8% longer than in control females. Length of the mesenteric intestine in pregnant and lactating females also increased 12.1% on average compared with the control group. The greatest changes in the alimentary canal occurred in the mucous membrane of the small intestine in pregnant and lactating females. The longest villi were found in the duodenum and the proximal part of the mesenteric intestine in these groups. The effect of these changes is an increase of digestive and absorptive area of the duodenum and proximal and intermediate regions of the mesenteric intestine. The entire area of the mucous membrane of the small intestine was 49.1% greater in lactating females than in control females and those at the early stage of gestation, and 20.5% higher in comparison with females in late gestation.