Preliminary observations on immunocytochemical localization of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) were made in 35 placentae of normal pregnancy at various stages of development. By analysing the processing regularities of the two hormones and comparing the characteristics of immunocytochemical localization and hematoxylin-eosin stain on various trophoblasts in the normal placentae, the findings showed: (1) presence of the three types of trophoblasts, namely, cytotrophoblast (CT), intermediate trophoblast (IT), and syncytiotrophoblast (ST) was confirmed in normal placentae of first-trimester pregnancy. (2) IT has distinctive immunocytochemical features that distinguishes itself from CT and ST. In the first-trimester, ST contains a large amount of hCG which sharply diminishes thereafter, but hPL in ST increases with the fetal age. IT contains hPL all through the pregnancy period and the peak-value occurs in the second trimester. CT is devoid of hCG and hPL. The results indicated: (1) IT is more like ST but different from CT. (2) IT contains chiefly hPL and hCG only locally in early pregnancy which demonstrates that the processing of hPL is in the more well differentiated cells whereas hCG is in the less differentiated cells.