The frequency and severity of local complications remain the primary safety issues with silicone breast implants. The Danish Registry for Plastic Surgery of the Breast (DPB), established in 1999, prospectively collects pre-, peri- and postoperative information regarding Danish women undergoing breast augmentation. Through DPB, we conducted a prospective follow-up study of short-term local complications among 1090 women who underwent cosmetic breast implantation from June 1999 through October 2002. Nineteen percent of women who underwent initial implantation developed at least 1 adverse effect. Forty percent of the adverse effects occurred within 3 months of implantation; 79%, within 6 months. Capsular contracture grade II-IV was observed among 4.1% of women in the 2-year follow-up period. Overall, 97 (29%) of the 344 adverse effects among 55 (6%) of the 971 women required surgical intervention. A higher incidence of adverse effects typically occurred after subsequent implantations. According to the DPB experience, we conclude that most short-term postoperative adverse effects following cosmetic implantation are clinically insignificant and do not require treatment and that short-term complications requiring adjuvant treatment are rare.