Polyacrylamide hydrogel (PAAG) has been widely used for injection augmentation mammaplasty in Russia, China, and Iran for more than 2 decades. In recent years, it has been advocated as a safe permanent filler for soft-tissue augmentation. However, the complications associated with PAAG injection in soft-tissue augmentation have not been extensively investigated. Augmentation mammaplasty through PAAG injection is associated with some complications. The incidence of infection during breastfeeding was reported to be higher than 50%. Herein, we report 58 cases of infection in breastfeeding women receiving PAAG injection, including 50 with unilateral injection (36 on the right, 14 on the left) and 8 bilateral injection. They experienced large breast autoinflation and some severe symptoms, such as local and systemic fever, breast swelling, nipple bulging, tenderness, and pain, which lead to surgical removal of galactocele or intraprosthetic collection of sterile pus resulting in deformity. Operation and comprehensive measures including removal of the injected material, clearing residual cavity, and pharmacotherapy were carried out to control infection and inflammation for 1 to 2 weeks. In the following 12 months, no relapse or recurrence of residual cavity was noted. Therefore, we do not recommend PAAG injection for augmentation mammaplasty, especially in women intending to breastfeed. Patients undergoing PAAG injection for augmentation mammaplasty should avoid breastfeeding. PAAG injection will cause serious consequences resulting in tissue atrophy and breast resection if inappropriately handled.