Abstract: Placenta, an important organ, mediates the exchange of nutrients and metabolites between mother and fetus. The transporters, including ATP-binding cassette (ABC) transporters and solute carrier (SLC), expressed in the syncytiotrophoblast play a vital role in substance exchange. Some transporters, such as organic cation transporters (OCTs) and organic anion transporters (OATs), mediate the uptake of endogenous substances and drugs. Some transporters, such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins (MRPs), can excrete their substrates from the syncytiotrophoblast to the maternal circulation. However, the expression and activity of these transporters are not uniform throughout the gestation period, since they can be affected by physiological and pathological changes during pregnancy or drugs. Thus, an understanding of the role of placental transporters and the variation in their expression and activity in response to physiological and pathological changes is essential for efficient and safe therapy during pregnancy, and it also has important value in the development of drug treatment in pregnancy.