It is found that in developing human placenta α-glucosidase is present in all subcellular fractions, maximum enzyme activity being associated with the supernatant fraction (S) of 10 to 26 weeks placenta. However, at very early (6-10 weeks) and late (36-40 weeks) gestation, the maximum enzyme activity is observed in the mitrochondrial fraction (P 2 ). α-glucosidase activity in the different subcellular fractions of placenta increases significantly with gestational age until 26 weeks. At term, the enzyme activity diminishes significantly from that at 22 to 26 weeks though being higher than that observed in the early gestation. The progressive increase in the enzyme activity with the increase in gestation shows a positive correlation of this enzyme with the growth and developmental processes of this rapidly growing tissue. The declined activity at term possibly accounts for the decreased physiological function and ageing of the tissue.