Serum levels of human placental lactogen have been measured by hemagglutination-inhibition reaction in 67 normal pregnant state and in 15 postpartum 24 hour state, HAIR is less sensitive and reliable method than radioimmunoassay, but simple, rapid, less expensive and fairly accurate, so it is more helpful in screening of large antenatal population with or without high risk complications. 1) Sensitivity of HPL-HAIR test kit was $0.1{mu}g$/ml of H.P.L. serum level and had no cross reaction to HCG or male serum or non-pregenant female or newborn infant, 2) H.P.L. value was around $2{mu}g$/ml until 24th week of pregnancy and rose to $6{sim}8$ ${mu}g$/ml continuously until about 36th week of pregnancy and then slightly decreased or stationary. 3) H.P.L. value in postpartum 24 hour state was undetectable. 4) There was poor correlation between maternal serum H.P.L. value at term and baby weight.