Little is known about why some patients experience recurrent seromas over the implant package and in the absence of any cause, antibiotics are frequently prescribed as a precaution to protect the implant from infection. A tertiary referral centre selected five patients who presented for review with a current or past history of seroma and retrospectively investigated their case notes. They found that the first occurrence of the seroma was normally years after initial implantation (average being 3.1 years). Aetiological investigations did not identify one singular cause with some being attributed to a minor trauma to the implant site, while others were preceded by an upper respiratory tract infection. One patient underwent thorough investigation of the seroma itself, using CT and ultrasound scanning, exploration, biopsy and allergy testing. Another patient had repeated ultrasound scanning, blood tests and aspiration. Pressure bandages were used in two out of the five. After looking at the series, the team concluded that the cause of the seromas was unknown, but possible hypotheses included abnormal immune response to a viral infection, minor injury or a biofilm formation. They felt that investigation of the seroma itself had proved unhelpful. Treatment was often the prescription of prophylactic antibiotics, but four out of the five patients had a least one episode where antibiotics were not taken and the seroma resolved spontaneously. They therefore recommended that antibiotics should be prescribed for the initial presentation of the seroma, but not given for subsequent episodes. They also suggest that a full blood count may be useful and extensive investigations should be avoided.