Objectives The aim of this study was to evaluate the effect of a dietary supplement containing porcine placenta on skin hydration. Methods The study was a randomized, placebo-controlled, double-blind, clinical trial. Forty-five healthy subjects without skin problems or diseases were enrolled and randomly divided into three groups who were respectively given a placebo, a dietary supplement containing porcine placenta extract (DSPPE), and a dietary supplement containing a vitamin (DSV) group. The subjects were given three capsules daily (including porcine placenta extract (containing 600 jug of Glycyl-L-Leucine (Gly-Leu) +L-Leucyl-Glycine (Leu-Gly) dipeptides)) for eight weeks. Skin hydration and transepidermal water loss (TEWL) were evaluated using Corneometer CM 825 and Tewameter TM300® devices. A quality-of-life (QOL) questionnaire and blood samples were tested to assess the safety of the test product. This study was registered in UMIN-CTR (UMIN 000026030). Results There was a statistically significant difference in skin hydration levels after eight weeks on the cheek (P<0.05) and arm (P<0.01) between the placebo and the DSPPE groups. A significant increase was observed on the arm after eight weeks of DSPPE ingestion compared to that before ingestion (P<0.01). Moreover, TEWL data showed a tendency to decrease after four weeks and eight weeks of ingestion in the DSPPE intervention group from the cheek. The results of the blood test and the QOL questionnaire did not show any health risks from the use of these test supplements. No additional adverse events occurred. Conclusions These results suggest that the ingestion of DSPPE has the potential to improve skin hydration and skin conditions in healthy subjects.