Classic teaching has stated that women who have undergone bilateral tubal ligation (BTL) are not susceptible to pelvic inflammatory disease (PID). The purpose of this study was to confirm the existence of PID in patients with BTL and to compare clinical parameters of these patients with PID patients who have not had BTL. A retrospective chart review of emergency department (ED) patients diagnosed with PID over a 1-year period at a large urban university hospital found 209 patients who fulfilled the criteria for a definition of PID. Of the 209 patients with PID, 24 (11.7%) had undergone BTL. Patients with and without BTL were compared with respect to age, white blood cell count (WBC), temperature, admission rate, length of hospitalization, prior history of PID, culture results, presence of bilateral abdominal pain, presence of rebound tenderness, and complications of tubo-ovarian abscess (TOA) and hydrosalpinx. Patients with BTL had lower WBCs (11,100/microL v14,700/microL) and were 2.5 times less likely to be hospitalized compared to those patients without BTL. These results show that PID in the setting of a prior BTL not only exists but occurs with surprising frequency and deserves further study. Patients with BTL and PID may have a clinically milder form of PID than those patients without BTL.