Introduction Pregnancy is a normal physiological state of woman that occurs with a implantation of the fertilized egg in the endometrium of the uterus. According to the Health Care Act, every pregnant woman between eighth and tenth week of pregnancy is tested for sexually transmitted diseases, that is for hepatitis B. Except of hepatitis B, people can be infected with other types of hepatitis, primarily with A and C, or less frequently, with hepatitis D and E. The newborn babies of hepatitis B positive mothers are in the most vulnerable group so the testing for HBsAg marker has exceptional importance in pregnant women. The majority of people get infected by hepatitis B through sexual contact, by subjecting to the various medical procedures and tattooing. Objective Objective of this paper is to point out the importance of correct analysis of the serological test for hepatitis B in pregnant women and its importance in clinical practice. Data sources and methods Proper Laboratory practice demands carefully guided protocols and work instructions for processing the analyte. Every step in preanalytical, analytical and postanalytical part is important during the testing for hepatitis B markers in pregnant women. Properly filled prescription, as well as blood sampling are mandatory preconditions for secure identification and analysis of the sample. The samples for HBsAg detection are taken into yellow, biochemical tubes that contains the gel. After centrifugation, samples are transferred to the Architect Abbott, the apparatus which can on the principle of immunochemical method qualitatively determine HBsAg in human serum or plasma. HBsAg negative results are attached to pregnancy book while HBsAg positive women are called for further tests and as well for the examination of hepatologist and/ or infectologist. Discussion The discussion presents the case of a pregnant woman who was admitted to the emergency hospital transfusion unit. Also there are given some examples of HBsAg positive pregnant women and comment. Conclusion The importance of sensitivity and proper performance of the test for hepatitis B in women during pregnancy is resulting from the simplicity and quality of test which can provide absolutely safe pregnancy and a healthy outcome for both mother and baby. Screening is mandatory, free and painless, therefore every pregnant woman should be tested to provide the best quality health care. HBsAg positive test result in the case of pregnancy requires immunoprophylaxis and vaccination of newborns. Also it is recommended to vaccinate sexual partners and family members.