PURPOSE: Soft-tissue augmentation using hyaluronic acid (HA) gels is widely used in dermatology and plastic surgery. We performed this study to determine the feasibility of using HA gel to augment the glans penis. MATERIALS AND METHODS: In experiment I, 0.2 cc of HA gel was injected into the dermis of the glans penis of 25 New Zealand White rabbits via a 27-gauge needle. At 3, 7, 14, 30, and 90 days after injection, the histologic changes in the penis and systemic adverse effects were evaluated. In experiment II, 0.5 cc of HA gel was injected into the dermis of the glans penis of 14 Beagle dogs. Two weeks later, an additional 0.2 cc was injected in 7 of the dogs. For 6 months, the changes in the injected area were grossly evaluated using a 10-point visual scale, and at the end of the study, histologic changes were also evaluated. At autopsy, lung, liver, and spleen were studied for systemic adverse reactions. RESULTS: In the dogs receiving double injections, 85% to 90% of the initial volume was maintained at 6 months, with HA being identified in the lamina propria of the glans penis. Encapsulated material was confirmed to be HA by alcian blue stain and hyaluronidase immunohistochemical stain. No systemic adverse reaction was noticed in any animal. CONCLUSIONS: Hyaluronic acid gel is safe and effective for augmentation of the glans penis. Booster injection enhances the injected volume and facilitates injection of HA.