Pelvic lymph node invasion is an important prognostic factor for cervical cancer. It is generally accepted that iliac lymph nodes must be treated systematically, but the extent of lymph node dissections is open to discussion. One hundred and eighty two cases of cervical cancer with lymph node invasion were treated at the Institut Curie between 1960 and 1988, by colpohysterectomy with lymph node dissection (168 cases) combined with preoperative brachytherapy and, in some cases, pre- and/or postoperative radiotherapy; in 14 cases, only an exploratory operation was performed. External iliac lymph node invasion was found in 95% of cases, situated in the middle and internal chains. Common iliac lymph node invasion was found in 24% of cases, but was only exceptionally isolated (3%). It is therefore possible, by means of well defined, localized external iliac dissection, with frozen section histological examination, to determine the exact lymph node status. Lumboaortic lymph node invasion was found in 8.2% of cases. The overall survival rate was 49% at 5 years and 40.5% at 10 years. Factors which influence survival are: the cervical volume (p = 0.015), the unilateral or bilateral nature of invasion (p = 0.0015), the number of lymph nodes invaded (two or more than two) (p = 0.0001), capsular rupture (p = 0.0008), lymph node adhesions other than venous (p = 0.0002), common iliac invasion (p = 0.0001). On Cox's model, the principal factors were the number of lymph nodes invaded, adhesion other than venous, common iliac invasion; on the other hand, venous adhesion does not modify the prognosis. The five-year survival rates following external iliac dissections and complete pelvic dissections were not significantly different. Finally, postoperative radiotherapy ensured a higher five-year survival rate than preoperative radiotherapy, but the cervical volume was greater and primary invasion was more frequent in these cases. Postoperative radiotherapy of 15 grays after preoperative radiotherapy did not appear to modify the survival and therefore appears to be useless.