Pelvic actinomycosis is well-known to be associated with the longstanding use of intrauterine devices, sometimes related with a pregnancy history and an obstetric and/or gynecologic surgery. It can extend to the retroperitoneum and may also be associated with ureteral obstruction. In this case, pelvic actinomycosis in the form of bilateral tubo-ovarian abscess extending to the retroperitoneum resulting in bilateral hydronephrosis occurred in a nulligravida woman who had only few prior sexual intercourses. Apparently, pelvic actinomycosis can occur without any specific history. Moreover, such could possibly give rise to hydronephrosis by direct extension to the retroperitoneum.