BACKGROUND The incidence of septic arthritis of a native joint caused by group B streptococcus (GBS, Streptococcus agalactiae) has been on the rise in non-pregnant women. GBS commonly colonizes the female genital tract. However, only a few reports have discussed serious cases of GBS infection, endocarditis, and joint infection associated with the Papanicolaou (Pap) smear test, which is routinely conducted to detect cervical cancer. Specifically, to the best of our knowledge, there have been few reports about arthroscopic treatment for septic arthritis of the ankle caused by GBS. CASE REPORT A 60-year-old woman, who had previously completed the treatment of total laparoscopic hysterectomy with bilateral adnexectomy and postoperative chemotherapy for ovarian cancer, underwent a routine Pap smear test. Four weeks later, she suddenly presented with high fever and abdominal pain. The pain and swelling in her left ankle gradually worsened. Finally, septic arthritis of the ankle was diagnosed, and thus the patient underwent emergent arthroscopic irrigation and debridement. GBS was isolated from both the ankle fluid and blood culture. After surgical intervention and intravenous antibiotic administration, the patient's symptoms gradually improved. Four months later, the patient had no ankle pain or restriction of ankle motion. CONCLUSIONS Although cervical cytology tests are essential in screening for cervical cancer, transient bacteremia can be induced by the tests. Thus, physicians must watch out for the development of septic arthritis caused by GBS when patients present with fever or swollen joints after a recent Pap smear test. Emergent diagnosis and appropriate surgical intervention is also important.